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Kaze AD, Santhanam P, Ahima RS, Bertoni AG, Echouffo-Tcheugui JB. Association Between Microvascular Disease and Cardiorespiratory Fitness Among Adults With Type 2 Diabetes. Diabetes Care 2024; 47:1408-1414. [PMID: 38837904 PMCID: PMC11272972 DOI: 10.2337/dc24-0294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Accepted: 05/06/2024] [Indexed: 06/07/2024]
Abstract
OBJECTIVE Little is known about the extent to which microvascular disease is associated with cardiorespiratory fitness (CRF) among individuals with type 2 diabetes. RESEARCH DESIGN AND METHODS A total of 4,766 participants with type 2 diabetes underwent maximal exercise testing in the Look AHEAD (Action for Health in Diabetes) study at baseline. Low CRF was defined based on the Aerobics Center Longitudinal Study reference standards. Microvascular disease was defined as having one or more of diabetes-related kidney disease (DKD), retinopathy, and neuropathy. The burden of microvascular disease was defined as the number of microvascular beds affected. RESULTS Of the 4,766 participants (mean age 58.9 ± 6.7 years, 58.5% women, 66.1% White individuals), 1,761 (37%) had microvascular disease. Participants with microvascular complications in three vascular territories had a lower CFR than those without any microvascular disease (mean adjusted metabolic equivalent of task [MET] 6.58 vs. 7.26, P = 0.001). Participants with any microvascular disease had higher odds of low CRF than those without microvascular disease (adjusted odds ratio [OR] 1.45, 95% CI 1.24-1.71). An increasing burden of microvascular disease was associated with higher odds of low CRF (for microvascular disease in three vascular territories, adjusted OR 2.82, 95% CI 1.36-5.85). Adjusted ORs for low CRF were 1.24 (95% CI 0.99-1.55), 1.34 (95% CI 1.02-1.76), and 1.44 (95% CI 1.20-1.73) for neuropathy, retinopathy, and DKD associations, respectively. CONCLUSIONS In a large cohort of adults with type 2 diabetes, the presence of microvascular disease and its burden were independently associated with lower CRF.
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Affiliation(s)
- Arnaud D. Kaze
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD
- Department of Medicine, LifePoint Health, Danville, VA
| | - Prasanna Santhanam
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD
| | - Rexford S. Ahima
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD
| | - Alain G. Bertoni
- Department of Epidemiology and Prevention, Wake Forest School of Medicine, Winston-Salem, NC
| | - Justin B. Echouffo-Tcheugui
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD
- Welch Prevention Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins University, Baltimore, MD
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2
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McDermott A, Nevin A, Gildea N, Rocha J, O'Shea D, Egaña M. Muscle deoxygenation during ramp incremental cycle exercise in older adults with type 2 diabetes. Eur J Appl Physiol 2024; 124:561-571. [PMID: 37638974 PMCID: PMC10858067 DOI: 10.1007/s00421-023-05297-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 08/03/2023] [Indexed: 08/29/2023]
Abstract
PURPOSE To explore profiles of fractional O2 extraction (using near-infrared spectroscopy) during ramp incremental cycling in older individuals with type 2 diabetes (T2D). METHODS Twelve individuals with T2D (mean ± SD, age: 63 ± 3 years) and 12 healthy controls (mean age: 65 ± 3 years) completed a ramp cycling exercise. Rates of muscle deoxygenation (i.e., deoxygenated haemoglobin and myoglobin, Δ[HHb + Mb]) profiles of the vastus lateralis muscle were normalised to 100% of the response, plotted against absolute (W) and relative (%peak) power output (PO) and fitted with a double linear regression model. RESULTS Peak oxygen uptake (V̇O2peak) was significantly (P < 0.01) reduced in T2D (23.0 ± 4.2 ml.kg-1.min-1) compared with controls (28.3 ± 5.3 ml.kg-1.min-1). The slope of the first linear segment of the model was greater (median (interquartile range)) in T2D (1.06 (1.50)) than controls (0.79 (1.06)) when Δ%[HHb + Mb] was plotted as a function of PO. In addition, the onset of the second linear segment of the Δ%[HHb + Mb]/PO model occurred at a lower exercise intensity in T2D (101 ± 35 W) than controls (140 ± 34 W) and it displayed a near-plateau response in both groups. When the relationship of the Δ%[HHb + Mb] profile was expressed as a function of %PO no differences were observed in any parameters of the double linear model. CONCLUSIONS These findings suggest that older individuals with uncomplicated T2D demonstrate greater fractional oxygen extraction for a given absolute PO compared with older controls. Thus, the reductions in V̇O2peak in older people with T2D are likely influenced by impairments in microvascular O2 delivery.
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Affiliation(s)
- Adam McDermott
- Department of Physiology, School of Medicine, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland
| | - Aaron Nevin
- Department of Physiology, School of Medicine, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland
| | - Norita Gildea
- Department of Physiology, School of Medicine, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland
| | | | - Donal O'Shea
- Endocrinology, St Columcille's and St Vincent's Hospitals, Dublin, Ireland
| | - Mikel Egaña
- Department of Physiology, School of Medicine, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland.
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3
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Butenas ALE, Copp SW, Hageman KS, Poole DC, Musch TI. Effects of comorbid type II diabetes mellitus and heart failure on rat hindlimb and respiratory muscle blood flow during treadmill exercise. J Appl Physiol (1985) 2023; 134:846-857. [PMID: 36825642 PMCID: PMC10042612 DOI: 10.1152/japplphysiol.00770.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 02/10/2023] [Accepted: 02/17/2023] [Indexed: 02/25/2023] Open
Abstract
In rats with type II diabetes mellitus (T2DM) compared with nondiabetic healthy controls, muscle blood flow (Q̇m) to primarily glycolytic hindlimb muscles and the diaphragm muscle are elevated during submaximal treadmill running consequent to lower skeletal muscle mass, a finding that held even when muscle mass was normalized to body mass. In rats with heart failure with reduced ejection fraction (HF-rEF) compared with healthy controls, hindlimb Q̇m was lower, whereas diaphragm Q̇m is elevated during submaximal treadmill running. Importantly, T2DM is the most common comorbidity present in patients with HF-rEF, but the effect of concurrent T2DM and HF-rEF on limb and respiratory Q̇m during exercise is unknown. We hypothesized that during treadmill running (20 m·min-1; 10% incline), hindlimb and diaphragm Q̇m would be higher in T2DM Goto-Kakizaki rats with HF-rEF (i.e., HF-rEF + T2DM) compared with nondiabetic Wistar rats with HF-rEF. Ejection fractions were not different between groups (HF-rEF: 30 ± 5; HF-rEF + T2DM: 28 ± 8%; P = 0.617), whereas blood glucose was higher in HF-rEF + T2DM (209 ± 150 mg/dL) compared with HF-rEF rats (113 ± 28 mg/dL; P = 0.040). Hindlimb muscle mass normalized to body mass was lower in rats with HF-rEF + T2DM (36.3 ± 1.6 mg/g) than in nondiabetic HF-rEF counterparts (40.3 ± 2.7 mg/g; P < 0.001). During exercise, Q̇m was elevated in rats with HF-rEF + T2DM compared with nondiabetic counterparts to the hindlimb (HF-rEF: 100 ± 28; HF-rEF + T2DM: 139 ± 23 mL·min-1·100 g-1; P < 0.001) and diaphragm (HF-rEF: 177 ± 66; HF-rEF + T2DM: 215 ± 93 mL·min-1·100g-1; P = 0.035). These data suggest that the pathophysiological consequences of T2DM on hindlimb and diaphragm Q̇m during treadmill running in the GK rat persist even in the presence of HF-rEF.NEW & NOTEWORTHY Herein, we demonstrate that rats comorbid with heart failure with reduced ejection fraction (HF-rEF) and type II diabetes mellitus (T2DM) have a higher hindlimb and respiratory muscle blood flow during submaximal treadmill running (20 m·min-1; 10% incline) compared with nondiabetic HF-rEF counterparts. These data may carry important clinical implications for roughly half of all patients with HF-rEF who present with T2DM.
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Affiliation(s)
- Alec L E Butenas
- Department of Kinesiology, Kansas State University, Manhattan, Kansas, United States
| | - Steven W Copp
- Department of Kinesiology, Kansas State University, Manhattan, Kansas, United States
| | - K Sue Hageman
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas, United States
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, Kansas, United States
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas, United States
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, Kansas, United States
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas, United States
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4
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Yamamoto H, Eshima H, Kakehi S, Kawamori R, Watada H, Tamura Y. Impaired fatigue resistance, sarcoplasmic reticulum function, and mitochondrial activity in soleus muscle of db/db mice. Physiol Rep 2022; 10:e15478. [PMID: 36117307 PMCID: PMC9483406 DOI: 10.14814/phy2.15478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 08/26/2022] [Accepted: 09/05/2022] [Indexed: 11/24/2022] Open
Abstract
Type 2 diabetes mellitus (T2DM) is characterized by reduced exercise tolerance due to increased fatigability in skeletal muscle. In this study, we investigated muscle fatigue resistance of soleus (SOL) muscle in obese type 2 diabetic model mice (db/db). No differences in muscle volume, absolute force, or specific force in SOL muscle were observed between db/db mice and control mice (db/+), while fatigue resistance evaluated by repeated tetanic contractions was significantly lower in db/db mice (30th tetani, db/+: 63.7 ± 4.7%, db/db: 51.3 ± 4.8%). The protein abundance related to Ca2+ release from the sarcoplasmic reticulum (SR) in SOL muscle was not different between db/db mice and db/+ mice, while SR Ca2+ -ATPase (Ca2+ reuptake to SR) protein was decreased in db/db mice compared to db/+ mice (db/+: 1.00 ± 0.17, db/db: 0.60 ± 0.04, relative units). In addition, mitochondrial oxidative enzyme activity (succinate dehydrogenase) was decreased in the SOL muscle of db/db mice (p < 0.05). These data suggest that fatigue resistance in slow-twitch dominant muscle is impaired in mice with T2DM. Decreased mitochondrial oxidative enzyme activity and impairment of Ca2+ uptake to SR, or both might be involved in the mechanisms.
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Affiliation(s)
- Hiro Yamamoto
- Department of International TourismNagasaki International UniversityNagasakiJapan
| | - Hiroaki Eshima
- Department of International TourismNagasaki International UniversityNagasakiJapan
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
- Sportology CenterJuntendo University Graduate School of MedicineTokyoJapan
| | - Saori Kakehi
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
- Sportology CenterJuntendo University Graduate School of MedicineTokyoJapan
| | - Ryuzo Kawamori
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
- Sportology CenterJuntendo University Graduate School of MedicineTokyoJapan
| | - Hirotaka Watada
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
- Sportology CenterJuntendo University Graduate School of MedicineTokyoJapan
- Center for Therapeutic Innovations in DiabetesJuntendo University Graduate School of MedicineTokyoJapan
- Center for Identification of Diabetic Therapeutic TargetsJuntendo University Graduate School of MedicineTokyoJapan
| | - Yoshifumi Tamura
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
- Sportology CenterJuntendo University Graduate School of MedicineTokyoJapan
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5
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Horn AG, Schulze KM, Weber RE, Barstow TJ, Musch TI, Poole DC, Behnke BJ. Post-occlusive reactive hyperemia and skeletal muscle capillary hemodynamics. Microvasc Res 2022; 140:104283. [PMID: 34822837 PMCID: PMC8830587 DOI: 10.1016/j.mvr.2021.104283] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 11/12/2021] [Accepted: 11/16/2021] [Indexed: 10/19/2022]
Abstract
Post-occlusive reactive hyperemia (PORH) is an accepted diagnostic tool for assessing peripheral macrovascular function. While conduit artery hemodynamics have been well defined, the impact of PORH on capillary hemodynamics remains unknown, despite the microvasculature being the dominant site of vascular control. Therefore, the purpose of this investigation was to determine the effects of 5 min of feed artery occlusion on capillary hemodynamics in skeletal muscle. We tested the hypothesis that, upon release of arterial occlusion, there would be: 1) an increased red blood cell flux (fRBC) and red blood cell velocity (VRBC), and 2) a decreased proportion of capillaries supporting RBC flow compared to the pre-occlusion condition. METHODS In female Sprague-Dawley rats (n = 6), the spinotrapezius muscle was exteriorized for evaluation of capillary hemodynamics pre-occlusion, 5 min of feed artery occlusion (Occ), and 5 min of reperfusion (Post-Occ). RESULTS There were no differences in mean arterial pressure (MAP) or capillary diameter (Dc) between pre-occlusion and post-occlusion (P > 0.05). During 30 s of PORH, capillary fRBC was increased (pre: 59 ± 4 vs. 30 s-post: 77 ± 2 cells/s; P < 0.05) and VRBC was not changed (pre: 300 ± 24 vs. 30 s post: 322 ± 25 μm/s; P > 0.05). Capillary hematocrit (Hctcap) was unchanged across the pre- to post-occlusion conditions (P > 0.05). Following occlusion, there was a 20-30% decrease in the number of capillaries supporting RBC flow at 30 s and 300 s-post occlusion (pre: 92 ± 2%; 30 s-post: 66 ± 3%; 300 s-post: 72 ± 6%; both P < 0.05). CONCLUSION Short-term feed artery occlusion (i.e. 5 min) resulted in a more heterogeneous capillary flow profile with the presence of capillary no-reflow, decreasing the percentage of capillaries supporting RBC flow. A complex interaction between myogenic and metabolic mechanisms at the arteriolar level may play a role in the capillary no-reflow with PORH. Measurements at the level of the conduit artery mask significant alterations in blood flow distribution in the microcirculation.
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Affiliation(s)
- Andrew G Horn
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States of America.
| | - Kiana M Schulze
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States of America
| | - Ramona E Weber
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States of America
| | - Thomas J Barstow
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States of America
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States of America; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States of America
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States of America; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States of America
| | - Bradley J Behnke
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States of America; Johnson Cancer Research Center, Kansas State University, Manhattan, KS, United States of America
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6
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Williams IM, Wasserman DH. Capillary Endothelial Insulin Transport: The Rate-limiting Step for Insulin-stimulated Glucose Uptake. Endocrinology 2022; 163:6462374. [PMID: 34908124 PMCID: PMC8758342 DOI: 10.1210/endocr/bqab252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Indexed: 11/19/2022]
Abstract
The rate-limiting step for skeletal muscle glucose uptake is transport from microcirculation to muscle interstitium. Capillary endothelium poses a barrier that delays the onset of muscle insulin action. Defining physiological barriers that control insulin access to interstitial space is difficult because of technical challenges that confront study of microscopic events in an integrated physiological system. Two physiological variables determine muscle insulin access. These are the number of perfused capillaries and the permeability of capillary walls to insulin. Disease states associated with capillary rarefaction are closely linked to insulin resistance. Insulin permeability through highly resistant capillary walls of muscle poses a significant barrier to insulin access. Insulin may traverse the endothelium through narrow intercellular junctions or vesicular trafficking across the endothelial cell. Insulin is large compared with intercellular junctions, making this an unlikely route. Transport by endothelial vesicular trafficking is likely the primary route of transit. Studies in vivo show movement of insulin is not insulin receptor dependent. This aligns with single-cell transcriptomics that show the insulin receptor is not expressed in muscle capillaries. Work in cultured endothelial cell lines suggest that insulin receptor activation is necessary for endothelial insulin transit. Controversies remain in the understanding of transendothelial insulin transit to muscle. These controversies closely align with experimental approaches. Control of circulating insulin accessibility to skeletal muscle is an area that remains ripe for discovery. Factors that impede insulin access to muscle may contribute to disease and factors that accelerate access may be of therapeutic value for insulin resistance.
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Affiliation(s)
- Ian M Williams
- Department of Molecular Physiology and Biophysics and Vanderbilt Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, TN 37232-0615, USA
| | - David H Wasserman
- Department of Molecular Physiology and Biophysics and Vanderbilt Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, TN 37232-0615, USA
- Correspondence: David H. Wasserman, PhD, Light Hall Rm. 702, Vanderbilt University, Nashville, TN 37232-0615, USA.
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7
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Burghard M, Takken T, Nap-van der Vlist MM, Nijhof SL, van der Ent CK, Heijerman HGM, Hulzebos HJE. Physiological predictors of cardiorespiratory fitness in children and adolescents with cystic fibrosis without ventilatory limitation. Ther Adv Respir Dis 2022; 16:17534666211070143. [PMID: 35012387 PMCID: PMC8755930 DOI: 10.1177/17534666211070143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Objectives: [1] To investigate the cardiorespiratory fitness (CRF) levels in children and
adolescents with cystic fibrosis (CF) with no ventilatory limitation
(ventilatory reserve ⩾ 15%) during exercise, and [2] to assess which
physiological factors are related to CRF. Methods: A cross-sectional study design was used in 8- to 18-year-old children and
adolescents with CF. Cardiopulmonary exercise testing was used to determine
peak oxygen uptake normalized to body weight as a measure of CRF. Patients
were defined as having ‘low CRF’ when CRF was less than 82%predicted.
Physiological predictors used in this study were body mass index z-score,
P. Aeruginosa lung infection, impaired glucose
tolerance (IGT) including CF-related diabetes, CF-related liver disease,
sweat chloride concentration, and self-reported physical activity. Backward
likelihood ratio (LR) logistic regression analysis was used. Results: Sixty children and adolescents (51.7% boys) with a median age of 15.3 years
(25th–75th percentile: 12.9–17.0 years) and a mean percentage predicted
forced expiratory volume in 1 second of 88.5% (±16.9) participated. Mean
percentage predicted CRF (ppVO2peak/kg) was 81.4% (±12.4, range:
51%–105%). Thirty-three patients (55.0%) were classified as having ‘low
CRF’. The final model that best predicted low CRF included IGT
(p = 0.085; Exp(B) = 6.770) and P.
Aeruginosa lung infection (p = 0.095; Exp(B) = 3.945). This
model was able to explain between 26.7% and 35.6% of variance. Conclusions: CRF is reduced in over half of children and adolescents with CF with normal
ventilatory reserve. Glucose intolerance and P. Aeruginosa
lung infection seem to be associated to low CRF in children and adolescents
with CF.
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Affiliation(s)
- Marcella Burghard
- Child Development, Exercise, and Physical Literacy Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, P.O. Box 85090, 3508 EA Utrecht, The Netherlands.,Cystic Fibrosis Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Tim Takken
- Child Development, Exercise, and Physical Literacy Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Merel M Nap-van der Vlist
- Department of Social Pediatrics, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Sanne L Nijhof
- Department of Social Pediatrics, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands
| | - C Kors van der Ent
- Cystic Fibrosis Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands.,Department of Pediatric Pulmonology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Harry G M Heijerman
- Cystic Fibrosis Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands.,Division Heart and Lung, Department of Pulmonology, Cystic Fibrosis Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | - H J Erik Hulzebos
- Child Development, Exercise, and Physical Literacy Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.,Cystic Fibrosis Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
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8
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Oxygen flux from capillary to mitochondria: integration of contemporary discoveries. Eur J Appl Physiol 2022; 122:7-28. [PMID: 34940908 PMCID: PMC8890444 DOI: 10.1007/s00421-021-04854-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 11/18/2021] [Indexed: 01/03/2023]
Abstract
Resting humans transport ~ 100 quintillion (1018) oxygen (O2) molecules every second to tissues for consumption. The final, short distance (< 50 µm) from capillary to the most distant mitochondria, in skeletal muscle where exercising O2 demands may increase 100-fold, challenges our understanding of O2 transport. To power cellular energetics O2 reaches its muscle mitochondrial target by dissociating from hemoglobin, crossing the red cell membrane, plasma, endothelial surface layer, endothelial cell, interstitial space, myocyte sarcolemma and a variable expanse of cytoplasm before traversing the mitochondrial outer/inner membranes and reacting with reduced cytochrome c and protons. This past century our understanding of O2's passage across the body's final O2 frontier has been completely revised. This review considers the latest structural and functional data, challenging the following entrenched notions: (1) That O2 moves freely across blood cell membranes. (2) The Krogh-Erlang model whereby O2 pressure decreases systematically from capillary to mitochondria. (3) Whether intramyocyte diffusion distances matter. (4) That mitochondria are separate organelles rather than coordinated and highly plastic syncytia. (5) The roles of free versus myoglobin-facilitated O2 diffusion. (6) That myocytes develop anoxic loci. These questions, and the intriguing notions that (1) cellular membranes, including interconnected mitochondrial membranes, act as low resistance conduits for O2, lipids and H+-electrochemical transport and (2) that myoglobin oxy/deoxygenation state controls mitochondrial oxidative function via nitric oxide, challenge established tenets of muscle metabolic control. These elements redefine muscle O2 transport models essential for the development of effective therapeutic countermeasures to pathological decrements in O2 supply and physical performance.
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9
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Poole DC. Can exercise training help redress sexual dimorphism in type II diabetes outcomes? J Diabetes Complications 2022; 36:108099. [PMID: 34916148 DOI: 10.1016/j.jdiacomp.2021.108099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 11/24/2021] [Indexed: 10/19/2022]
Affiliation(s)
- David C Poole
- Department of Kinesiology and Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA.
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10
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Green S, Kiely C, O'Connor E, Gildea N, O'Shea D, Egaña M. Differential effects of sex on adaptive responses of skeletal muscle vasodilation to exercise training in type 2 diabetes. J Diabetes Complications 2022; 36:108098. [PMID: 34887186 DOI: 10.1016/j.jdiacomp.2021.108098] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 11/14/2021] [Accepted: 11/21/2021] [Indexed: 01/07/2023]
Abstract
AIMS We tested the hypotheses that exercise training improves the peak and dynamic responses of leg vascular conductance (LVC) in males and females with type 2 diabetes (T2DM). METHODS Forty-one males and females with T2DM were assigned to two training groups and two control groups. Twelve weeks of aerobic/resistance training was performed three times per week, 60-90 min per session. Responses of calf muscle blood flow and systemic arterial pressure during incremental and constant-load (30% maximal voluntary contraction) intermittent plantar-flexion protocols in the supine position were recorded. RESULTS Training significantly increased peak LVC in males (4.86 ± 1.88 to 6.06 ± 2.06 ml·min-1·mm Hg-1) and females (3.91 ± 1.13 to 5.40 ± 1.38 ml·min-1·mm Hg-1) with no changes in control groups. For dynamic responses, training significantly increased the amplitude of the fast growth phase of LVC (1.81 ± 1.12 to 2.68 ± 1.01 ml·min-1·mm Hg-1) and decreased the time constant of the slow growth phase (43.6 ± 46.4 s to 16.1 14.0 s) in females, but no improvements were observed in control females or in any of the two male groups. CONCLUSIONS These data suggest that training increases the peak vasodilatory response in males and females, whereas the speed of the dynamic response of vasodilation is improved in females but not males.
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Affiliation(s)
- Simon Green
- School of Health Sciences, Western Sydney University, Sydney, Australia; School of Medicine, Western Sydney University, Sydney, Australia
| | - Catherine Kiely
- School of Medicine, Department of Physiology, Trinity College Dublin, Dublin 2, Ireland
| | - Eamonn O'Connor
- School of Medicine, Department of Physiology, Trinity College Dublin, Dublin 2, Ireland
| | - Norita Gildea
- School of Medicine, Department of Physiology, Trinity College Dublin, Dublin 2, Ireland
| | - Donal O'Shea
- Department of Endocrinology, St. Columcille's Hospital, Dublin, Ireland; Department of Endocrinology and Diabetes Mellitus, St. Vincent's University Hospital, Dublin, Ireland
| | - Mikel Egaña
- School of Medicine, Department of Physiology, Trinity College Dublin, Dublin 2, Ireland.
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11
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Kaze AD, Agoons DD, Santhanam P, Erqou S, Ahima RS, Echouffo-Tcheugui JB. Correlates of cardiorespiratory fitness among overweight or obese individuals with type 2 diabetes. BMJ Open Diabetes Res Care 2022; 10:10/1/e002446. [PMID: 34987052 PMCID: PMC8734012 DOI: 10.1136/bmjdrc-2021-002446] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 10/17/2021] [Indexed: 11/04/2022] Open
Abstract
INTRODUCTION Mechanistic studies suggest that type 2 diabetes is independently associated with low cardiorespiratory fitness (CRF). Little is known about the CRF profile in type 2 diabetes; we assessed the correlates of low CRF among overweight/obese adults with type 2 diabetes. RESEARCH DESIGN AND METHODS A total of 4215 participants with type 2 diabetes and without cardiovascular disease underwent maximal exercise testing in the Look AHEAD (Action for Health in Diabetes) study. Low CRF was defined based on the Aerobics Center Longitudinal Study reference standards. Calorie intake and physical activity were assessed using questionnaires. Body fat composition was assessed using dual-energy X-ray absorptiometry. RESULTS Waist circumference, systolic blood pressure, glycemic measures, whole body fat, caloric intake, and fat-free mass were inversely associated with fitness across sex (all p<0.001). Comparing with moderate or high CRF groups, the low CRF group was associated with higher adjusted odds of obesity (OR 3.19 (95% CI 1.95 to 5.20) in men, 3.86 (95% CI 2.55 to 5.84)) in women), abdominal obesity (OR 3.99 (95% CI 2.00 to 7.96) in men, 2.28 (95% CI 1.08 to 4.79) in women), hypertension (OR 1.74 (95% CI 1.09 to 2.77) in men, 1.44 (95% CI 1.02 to 2.05) in women), metabolic syndrome (OR 5.52 (95% CI 2.51 to 12.14) in men, 2.25 (95% CI 1.35 to 3.76) in women), use of beta-blocker (1.22 (95% CI 0.86 to 1.73) in men, 1.33 (95% CI 1.03 to 1.73) in women), and ACE inhibitor/angiotensin-receptor blocker (1.86 (95% CI 1.39 to 2.50) in men, 1.07 (95% CI 0.86 to 1.32) in women). Women with low CRF had higher odds of current smoking (2.02 (95% CI 1.25 to 3.28)). CONCLUSIONS Low CRF was associated with increased odds of cardiometabolic correlates in a large cohort of adults with type 2 diabetes.
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Affiliation(s)
- Arnaud D Kaze
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Dayawa Da Agoons
- Department of Medicine, UPMC Pinnacle, Harrisburg, Pennsylvania, USA
| | - Prasanna Santhanam
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Sebhat Erqou
- Department of Medicine, Brown University Warren Alpert Medical School, Providence, Rhode Island, USA
| | - Rexford S Ahima
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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12
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Gildea N, McDermott A, Rocha J, O'Shea D, Green S, Egaña M. Time-course of V̇o 2 kinetics responses during moderate-intensity exercise subsequent to HIIT versus moderate-intensity continuous training in type 2 diabetes. J Appl Physiol (1985) 2021; 130:1646-1659. [PMID: 33792400 DOI: 10.1152/japplphysiol.00952.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We assessed the time-course of changes in oxygen uptake (V̇o2) and muscle deoxygenation (i.e., deoxygenated hemoglobin and myoglobin, [HHb + Mb]) kinetics during transitions to moderate-intensity cycling following 12 wk of low-volume high-intensity interval training (HIIT) vs. moderate-intensity continuous training (MICT) in adults with type 2 diabetes (T2D). Participants were randomly assigned to MICT (n = 10, 50 min of moderate-intensity cycling), HIIT (n = 9, 10 × 1 min at ∼90% maximal heart rate), or nonexercising control (n = 9) groups. Exercising groups trained three times per week, and measurements were taken every 3 wk. [HHb + Mb] kinetics were measured by near-infrared spectroscopy at the vastus lateralis muscle. The local matching of O2 delivery to O2 utilization was assessed by the Δ[HHb + Mb]/ΔV̇o2 ratio. The pretraining time constant of the primary phase of V̇o2 (τV̇o2p) decreased (P < 0.05) at wk 3 of training in both MICT (from 44 ± 12 to 32 ± 5 s) and HIIT (from 42 ± 8 to 32 ± 4 s) with no further changes thereafter, whereas no changes were reported in controls. The pretraining overall dynamic response of muscle deoxygenation (τ'[HHb + Mb]) was faster than τV̇o2p in all groups, resulting in Δ[HHb + Mb]/V̇o2p showing a transient "overshoot" relative to the subsequent steady-state level. After 3 wk, the Δ[HHb + Mb]/V̇o2p overshoot was eliminated only in the training groups, so that τ'[HHb + Mb] was not different to τV̇o2p in MICT and HIIT. The enhanced V̇o2 kinetics response consequent to both MICT and HIIT in T2D was likely attributed to a training-induced improvement in matching of O2 delivery to utilization.NEW & NOTEWORTHY High-intensity interval training and moderate-intensity continuous training elicited faster pulmonary oxygen uptake (V̇o2) kinetics during moderate-intensity cycling within 3 wk of training with no further changes thereafter in individuals with type 2 diabetes. These adaptations were accompanied by unaltered near-infrared spectroscopy-derived muscle deoxygenation (i.e. deoxygenated hemoglobin and myoglobin concentration, [HHb+Mb]) kinetics and transiently reduced Δ[HHb+Mb]-to-ΔV̇o2 ratio, suggesting an enhanced blood flow distribution within the active muscles subsequent to both training interventions.
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Affiliation(s)
- Norita Gildea
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Adam McDermott
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Joel Rocha
- Division of Sport and Exercise Sciences, Abertay University, Dundee, United Kingdom
| | - Donal O'Shea
- Department of Endocrinology, St. Columcille's Hospital, Dublin, Ireland.,Department of Endocrinology and Diabetes Mellitus, St. Vincent's University Hospital, Dublin, Ireland
| | - Simon Green
- Schools of Health Sciences and Medicine, Western Sydney University, Sydney, Australia
| | - Mikel Egaña
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
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13
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Mendelson AA, Milkovich S, Hunter T, Vijay R, Choi YH, Milkovich S, Ho E, Goldman D, Ellis CG. The capillary fascicle in skeletal muscle: Structural and functional physiology of RBC distribution in capillary networks. J Physiol 2021; 599:2149-2168. [PMID: 33595111 DOI: 10.1113/jp281172] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/04/2021] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS The capillary module, consisting of parallel capillaries from arteriole to venule, is classically considered as the building block of complex capillary networks. In skeletal muscle, this structure fails to address how blood flow is regulated along the entire length of the synchronously contracting muscle fibres. Using intravital video microscopy of resting extensor digitorum longus muscle in rats, we demonstrated the capillary fascicle as a series of interconnected modules forming continuous columns that align naturally with the dimensions of the muscle fascicle. We observed structural heterogeneity for module topology, and functional heterogeneity in space and time for capillary-red blood cell (RBC) haemodynamics within a module and between modules. We found that module RBC haemodynamics were independent of module resistance, providing direct evidence for microvascular flow regulation at the level of the capillary module. The capillary fascicle is an updated paradigm for characterizing blood flow and RBC distribution in skeletal muscle capillary networks. ABSTRACT Capillary networks are the fundamental site of oxygen exchange in the microcirculation. The capillary module (CM), consisting of parallel capillaries from terminal arteriole (TA) to post-capillary venule (PCV), is classically considered as the building block of complex capillary networks. In skeletal muscle, this structure fails to address how blood flow is regulated along the entire length of the synchronously contracting muscle fibres, requiring co-ordination from numerous modules. It has previously been recognized that TAs and PCVs interact with multiple CMs, creating interconnected networks. Using label-free intravital video microscopy of resting extensor digitorum longus muscle in rats, we found that these networks form continuous columns of linked CMs spanning thousands of microns, herein denoted as the capillary fascicle (CF); this structure aligns naturally with the dimensions of the muscle fascicle. We measured capillary-red blood cell (RBC) haemodynamics and module topology (n = 9 networks, 327 modules, 1491 capillary segments). The average module had length 481 μm, width 157 μm and 9.51 parallel capillaries. We observed structural heterogeneity for CM topology, and functional heterogeneity in space and time for capillary-RBC haemodynamics within a module and between modules. There was no correlation between capillary RBC velocity and lineal density. A passive inverse relationship between module length and haemodynamics was remarkably absent, providing direct evidence for microvascular flow regulation at the level of the CM. In summary, the CF is an updated paradigm for characterizing RBC distribution in skeletal muscle, and strengthens the theory of capillary networks as major contributors to the signal that regulates capillary perfusion.
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Affiliation(s)
- Asher A Mendelson
- Department of Medicine, Section of Critical Care Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Stephanie Milkovich
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Timothy Hunter
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Raashi Vijay
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Yun-Hee Choi
- Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Shaun Milkovich
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Edward Ho
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Daniel Goldman
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.,Department of Applied Mathematics, Faculty of Science, Western University, London, Ontario, Canada
| | - Christopher G Ellis
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.,Robarts Research Institute, London, Ontario, Canada
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14
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Poole DC, Behnke BJ, Musch TI. The role of vascular function on exercise capacity in health and disease. J Physiol 2021; 599:889-910. [PMID: 31977068 PMCID: PMC7874303 DOI: 10.1113/jp278931] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 12/10/2019] [Indexed: 12/16/2022] Open
Abstract
Three sentinel parameters of aerobic performance are the maximal oxygen uptake ( V ̇ O 2 max ), critical power (CP) and speed of the V ̇ O 2 kinetics following exercise onset. Of these, the latter is, perhaps, the cardinal test of integrated function along the O2 transport pathway from lungs to skeletal muscle mitochondria. Fast V ̇ O 2 kinetics demands that the cardiovascular system distributes exercise-induced blood flow elevations among and within those vascular beds subserving the contracting muscle(s). Ideally, this process must occur at least as rapidly as mitochondrial metabolism elevates V ̇ O 2 . Chronic disease and ageing create an O2 delivery (i.e. blood flow × arterial [O2 ], Q ̇ O 2 ) dependency that slows V ̇ O 2 kinetics, decreasing CP and V ̇ O 2 max , increasing the O2 deficit and sowing the seeds of exercise intolerance. Exercise training, in contrast, does the opposite. Within the context of these three parameters (see Graphical Abstract), this brief review examines the training-induced plasticity of key elements in the O2 transport pathway. It asks how structural and functional vascular adaptations accelerate and redistribute muscle Q ̇ O 2 and thus defend microvascular O2 partial pressures and capillary blood-myocyte O2 diffusion across a ∼100-fold range of muscle V ̇ O 2 values. Recent discoveries, especially in the muscle microcirculation and Q ̇ O 2 -to- V ̇ O 2 heterogeneity, are integrated with the O2 transport pathway to appreciate how local and systemic vascular control helps defend V ̇ O 2 kinetics and determine CP and V ̇ O 2 max in health and how vascular dysfunction in disease predicates exercise intolerance. Finally, the latest evidence that nitrate supplementation improves vascular and therefore aerobic function in health and disease is presented.
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Affiliation(s)
- David C Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Brad J Behnke
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Timothy I Musch
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
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15
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Colburn TD, Weber RE, Hageman KS, Caldwell JT, Schulze KM, Ade CJ, Behnke BJ, Poole DC, Musch TI. Vascular ATP-sensitive K + channels support maximal aerobic capacity and critical speed via convective and diffusive O 2 transport. J Physiol 2020; 598:4843-4858. [PMID: 32798233 PMCID: PMC7874302 DOI: 10.1113/jp280232] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 08/13/2020] [Indexed: 12/26/2022] Open
Abstract
KEY POINTS Oral sulphonylureas, widely prescribed for diabetes, inhibit pancreatic ATP-sensitive K+ (KATP ) channels to increase insulin release. However, KATP channels are also located within vascular (endothelium and smooth muscle) and muscle (cardiac and skeletal) tissue. We evaluated left ventricular function at rest, maximal aerobic capacity ( V ̇ O2 max) and submaximal exercise tolerance (i.e. speed-duration relationship) during treadmill running in rats, before and after systemic KATP channel inhibition via glibenclamide. Glibenclamide impaired critical speed proportionally more than V ̇ O2 max but did not alter resting cardiac output. Vascular KATP channel function (topical glibenclamide superfused onto hindlimb skeletal muscle) resolved a decreased blood flow and interstitial PO2 during twitch contractions reflecting impaired O2 delivery-to-utilization matching. Our findings demonstrate that systemic KATP channel inhibition reduces V ̇ O2 max and critical speed during treadmill running in rats due, in part, to impaired convective and diffusive O2 delivery, and thus V ̇ O2 , especially within fast-twitch oxidative skeletal muscle. ABSTRACT Vascular ATP-sensitive K+ (KATP ) channels support skeletal muscle blood flow and microvascular oxygen delivery-to-utilization matching during exercise. However, oral sulphonylurea treatment for diabetes inhibits pancreatic KATP channels to enhance insulin release. Herein we tested the hypotheses that: i) systemic KATP channel inhibition via glibenclamide (GLI; 10 mg kg-1 i.p.) would decrease cardiac output at rest (echocardiography), maximal aerobic capacity ( V ̇ O2 max) and the speed-duration relationship (i.e. lower critical speed (CS)) during treadmill running; and ii) local KATP channel inhibition (5 mg kg-1 GLI superfusion) would decrease blood flow (15 µm microspheres), interstitial space oxygen pressures (PO2 is; phosphorescence quenching) and convective and diffusive O2 transport ( Q ̇ O2 and DO2 , respectively; Fick Principle and Law of Diffusion) in contracting fast-twitch oxidative mixed gastrocnemius muscle (MG: 9% type I+IIa fibres). At rest, GLI slowed left ventricular relaxation (2.11 ± 0.59 vs. 1.70 ± 0.23 cm s-1 ) and decreased heart rate (321 ± 23 vs. 304 ± 22 bpm, both P < 0.05) while cardiac output remained unaltered (219 ± 64 vs. 197 ± 39 ml min-1 , P > 0.05). During exercise, GLI reduced V ̇ O2 max (71.5 ± 3.1 vs. 67.9 ± 4.8 ml kg-1 min-1 ) and CS (35.9 ± 2.4 vs. 31.9 ± 3.1 m min-1 , both P < 0.05). Local KATP channel inhibition decreased MG blood flow (52 ± 25 vs. 34 ± 13 ml min-1 100 g tissue-1 ) and PO2 isnadir (5.9 ± 0.9 vs. 4.7 ± 1.1 mmHg) during twitch contractions. Furthermore, MG V ̇ O2 was reduced via impaired Q ̇ O2 and DO2 (P < 0.05 for each). Collectively, these data support that vascular KATP channels help sustain submaximal exercise tolerance in healthy rats. For patients taking sulfonylureas, KATP channel inhibition may exacerbate exercise intolerance.
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Affiliation(s)
- Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Ramona E Weber
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - K Sue Hageman
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Jacob T Caldwell
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Kiana M Schulze
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Carl J Ade
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Brad J Behnke
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
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16
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Butenas ALE, Smith JR, Copp SW, Sue Hageman K, Poole DC, Musch TI. Type II diabetes accentuates diaphragm blood flow increases during submaximal exercise in the rat. Respir Physiol Neurobiol 2020; 281:103518. [PMID: 32777269 DOI: 10.1016/j.resp.2020.103518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 08/04/2020] [Accepted: 08/05/2020] [Indexed: 12/25/2022]
Abstract
We investigated the effect of type 2 diabetes mellitus (T2DM) on respiratory muscle blood flow (BF) during exercise. Using the Goto-Kakizaki (GK) rat model of T2DM, we hypothesized that diaphragm, intercostal and transverse abdominis BFs (radiolabeled microspheres) would be higher in male GK rats (n = 10) compared to healthy male Wistar controls (CON; n = 8) during submaximal exercise (20 m/min, 10 % grade). Blood glucose was significantly higher in GK (246 ± 29 mg/dL) compared to CON (103 ± 4 mg/dL; P < 0.01). Respiratory muscle BFs were not different at rest (P> 0.50). From rest to submaximal exercise, respiratory muscle BFs increased in both groups to all muscles (P < 0.01). During submaximal exercise GK rats had higher diaphragm BFs (GK: 189 ± 13; CON: 138 ± 14 mL/min/100 g, P < 0.01), and vascular conductance (GK: 1.4 ± 0.1; CON: 1.0 ± 0.1 mL/min/mmHg/100 g; P < 0.01) compared to CON. There were no differences in intercostal or transverse abdominis BF or VC during exercise (P> 0.15). These findings suggest that submaximal exercise requires a higher diaphragm BF and VC in T2DM compared to healthy counterparts.
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Affiliation(s)
- Alec L E Butenas
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States.
| | - Joshua R Smith
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States
| | - Steven W Copp
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States
| | - K Sue Hageman
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States
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17
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Colburn TD, Hirai DM, Craig JC, Ferguson SK, Weber RE, Schulze KM, Behnke BJ, Musch TI, Poole DC. Transcapillary PO 2 gradients in contracting muscles across the fibre type and oxidative continuum. J Physiol 2020; 598:3187-3202. [PMID: 32445225 DOI: 10.1113/jp279608] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 05/14/2020] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Within skeletal muscle the greatest resistance to oxygen transport is thought to reside across the short distance at the red blood cell-myocyte interface. These structures generate a significant transmural oxygen pressure (PO2 ) gradient in mixed fibre-type muscle. Increasing O2 flux across the capillary wall during exercise depends on: (i) the transmural O2 pressure gradient, which is maintained in mixed-fibre muscle, and/or (ii) elevating diffusing properties between microvascular and interstitial compartments resulting, in part, from microvascular haemodynamics and red blood cell distribution. We evaluated the PO2 within the microvascular and interstitial spaces of muscles spanning the slow- to fast-twitch fibre and high- to low-oxidative capacity spectrums, at rest and during contractions, to assess the magnitude of transcapillary PO2 gradients in rats. Our findings demonstrate that, across the metabolic rest-contraction transition, the transcapillary pressure gradient for O2 flux is: (i) maintained in all muscle types, and (ii) the lowest in contracting highly oxidative fast-twitch muscle. ABSTRACT In mixed fibre-type skeletal muscle transcapillary PO2 gradients (PO2 mv-PO2 is; microvascular and interstitial, respectively) drive O2 flux across the blood-myocyte interface where the greatest resistance to that O2 flux resides. We assessed a broad spectrum of fibre-type and oxidative-capacity rat muscles across the rest-to-contraction (1 Hz, 120 s) transient to test the novel hypotheses that: (i) slow-twitch PO2 is would be greater than fast-twitch, (ii) muscles with greater oxidative capacity have greater PO2 is than glycolytic counterparts, and (iii) whether PO2 mv-PO2 is at rest is maintained during contractions across all muscle types. PO2 mv and PO2 is were determined via phosphorescence quenching in soleus (SOL; 91% type I+IIa fibres and CSa: ∼21 μmol min-1 g-1 ), peroneal (PER; 33% and ∼20 μmol min-1 g-1 ), mixed (MG; 9% and ∼26 μmol min-1 g-1 ) and white gastrocnemius (WG; 0% and ∼8 μmol min-1 g-1 ) across the rest-contraction transient. PO2 mv was higher than PO2 is in each muscle (∼6-13 mmHg; P < 0.05). SOL PO2 isarea was greater than in the fast-twitch muscles during contractions (P < 0.05). Oxidative muscles had greater PO2 isnadir (9.4 ± 0.8, 7.4 ± 0.9 and 6.4 ± 0.4; SOL, PER and MG, respectively) than WG (3.0 ± 0.3 mmHg, P < 0.05). The magnitude of PO2 mv-PO2 is at rest decreased during contractions in MG only (∼11 to 7 mmHg; time × (PO2 mv-PO2 is) interaction, P < 0.05). These data support the hypothesis that, since transcapillary PO2 gradients during contractions are maintained in all muscle types, increased O2 flux must occur via enhanced intracapillary diffusing conductance, which is most extreme in highly oxidative fast-twitch muscle.
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Affiliation(s)
| | - Daniel M Hirai
- Department of Health and Kinesiology, Purdue University, West Lafayette, IN
| | - Jesse C Craig
- Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Scott K Ferguson
- Department of Kinesiology and Exercise Sciences, University of Hawaii, Hilo, HI
| | - Ramona E Weber
- Department of Kinesiology, Kansas State University Manhattan, KS
| | - Kiana M Schulze
- Department of Kinesiology, Kansas State University Manhattan, KS
| | - Brad J Behnke
- Department of Kinesiology, Kansas State University Manhattan, KS
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University Manhattan, KS.,Department of Anatomy and Physiology, Kansas State University Manhattan, KS
| | - David C Poole
- Department of Kinesiology, Kansas State University Manhattan, KS.,Department of Anatomy and Physiology, Kansas State University Manhattan, KS
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18
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Poole DC, Copp SW, Colburn TD, Craig JC, Allen DL, Sturek M, O'Leary DS, Zucker IH, Musch TI. Guidelines for animal exercise and training protocols for cardiovascular studies. Am J Physiol Heart Circ Physiol 2020; 318:H1100-H1138. [PMID: 32196357 DOI: 10.1152/ajpheart.00697.2019] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Whole body exercise tolerance is the consummate example of integrative physiological function among the metabolic, neuromuscular, cardiovascular, and respiratory systems. Depending on the animal selected, the energetic demands and flux through the oxygen transport system can increase two orders of magnitude from rest to maximal exercise. Thus, animal models in health and disease present the scientist with flexible, powerful, and, in some instances, purpose-built tools to explore the mechanistic bases for physiological function and help unveil the causes for pathological or age-related exercise intolerance. Elegant experimental designs and analyses of kinetic parameters and steady-state responses permit acute and chronic exercise paradigms to identify therapeutic targets for drug development in disease and also present the opportunity to test the efficacy of pharmacological and behavioral countermeasures during aging, for example. However, for this promise to be fully realized, the correct or optimal animal model must be selected in conjunction with reproducible tests of physiological function (e.g., exercise capacity and maximal oxygen uptake) that can be compared equitably across laboratories, clinics, and other proving grounds. Rigorously controlled animal exercise and training studies constitute the foundation of translational research. This review presents the most commonly selected animal models with guidelines for their use and obtaining reproducible results and, crucially, translates state-of-the-art techniques and procedures developed on humans to those animal models.
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Affiliation(s)
- David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Steven W Copp
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Jesse C Craig
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah
| | - David L Allen
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado
| | - Michael Sturek
- Department of Anatomy, Cell Biology and Physiology, Indiana University, Indianapolis, Indiana
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Irving H Zucker
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
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19
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Green S, Kiely C, O'Connor E, Gildea N, O'Shea D, Egaña M. Effects of exercise training and sex on dynamic responses of O 2 uptake in type 2 diabetes. Appl Physiol Nutr Metab 2020; 45:865-874. [PMID: 32134683 DOI: 10.1139/apnm-2019-0636] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Effects of training and sex on oxygen uptake dynamics during exercise in type 2 diabetes mellitus (T2DM) are not well established. We tested the hypotheses that exercise training improves the time constant of the primary phase of oxygen uptake (τp oxygen uptake) and with greater effect in males than females. Forty-one subjects with T2DM were assigned to 2 training groups (Tmale, Tfemale) and 2 control groups (Cmale, Cfemale), and were assessed before and after a 12-week intervention period. Twelve weeks of aerobic/resistance training was performed 3 times per week, 60-90 min per session. Assessments included ventilatory threshold (VT), peak oxygen uptake, τp oxygen uptake (80%VT), and dynamic responses of cardiac output, mean arterial pressure and systemic vascular conductance (80%VT). Training significantly decreased τp oxygen uptake in males by a mean of 20% (Tmale = 42.7 ± 6.2 to 34.3 ± 7.2 s) and females by a mean of 16% (Tfemale = 42.2 ± 9.3 to 35.4 ± 8.6 s); whereas τp oxygen uptake was not affected in controls (Cmale = 41.6 ± 9.8 to 42.9 ± 7.6 s; Cfemale = 40.4 ± 12.2 to 40.6 ± 13.4 s). Training increased peak oxygen uptake in both sexes (12%-13%) but did not alter systemic cardiovascular dynamics in either sex. Training improved oxygen uptake dynamics to a similar extent in males and females in the absence of changes in systemic cardiovascular dynamics. Novelty Similar training improvements in oxygen uptake dynamics were observed in males and females with T2DM. In both sexes these improvements occurred without changes in systemic cardiovascular dynamics.
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Affiliation(s)
- Simon Green
- School of Science and Health, Western Sydney University, Sydney 2567, Australia.,School of Medicine, Western Sydney University, Sydney 2567, Australia
| | - Catherine Kiely
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Eamonn O'Connor
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Norita Gildea
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Donal O'Shea
- Endocrinology, St Columcille's and St Vincent's Hospitals, Dublin, Dublin 18, Ireland
| | - Mikel Egaña
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin 2, Ireland
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Rocha J, Gildea N, O’Shea D, Green S, Egaña M. Influence of priming exercise on oxygen uptake and muscle deoxygenation kinetics during moderate-intensity cycling in type 2 diabetes. J Appl Physiol (1985) 2019; 127:1140-1149. [DOI: 10.1152/japplphysiol.00344.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The pulmonary oxygen uptake (V̇o2) kinetics during the transition to moderate-intensity exercise is slowed in individuals with type 2 diabetes (T2D), at least in part because of limitations in O2 delivery. The present study tested the hypothesis that a prior heavy-intensity warm-up or “priming” exercise (PE) bout would accelerate V̇o2 kinetics in T2D, because of a better matching of O2 delivery to utilization. Twelve middle-aged individuals with T2D and 12 healthy controls (ND) completed moderate-intensity constant-load cycling bouts either without (Mod A) or with (Mod B) prior PE. The rates of muscle deoxygenation (i.e., deoxygenated hemoglobin and myoglobin concentration, [HHb+Mb]) and oxygenation (i.e., tissue oxygenation index) were continuously measured by near-infrared spectroscopy at the vastus lateralis muscle. The local matching of O2 delivery to O2 utilization was assessed by the Δ[HHb+Mb]-to-ΔV̇o2 ratio. Both groups demonstrated an accelerated V̇O2 kinetics response during Mod B compared with Mod A (T2D, 32 ± 9 vs. 42 ± 12 s; ND, 28 ± 9 vs. 34 ± 8 s; means ± SD) and an elevated muscle oxygenation throughout Mod B, whereas the [HHb+Mb] amplitude was greater during Mod B only in individuals with T2D. The [HHb+Mb] kinetics remained unchanged in both groups. In T2D, Mod B was associated with a decrease in the “overshoot” relative to steady state in the Δ[HHb+Mb]-to-ΔV̇o2 ratio (1.17 ± 0.17 vs. 1.05 ± 0.15), whereas no overshoot was observed in the control group before (1.04 ± 0.12) or after (1.01 ± 0.12) PE. Our findings support a favorable priming-induced acceleration of the V̇o2 kinetics response in middle-aged individuals with uncomplicated T2D attributed to an enhanced matching of microvascular O2 delivery to utilization. NEW & NOTEWORTHY Heavy-intensity “priming” exercise (PE) elicited faster pulmonary oxygen uptake (V̇o2) kinetics during moderate-intensity cycling exercise in middle-aged individuals with type 2 diabetes (T2D). This was accompanied by greater near-infrared spectroscopy-derived muscle deoxygenation (i.e., deoxygenated hemoglobin and myoglobin concentration, [HHb+Mb]) responses and a reduced Δ[HHb+Mb]-to-ΔV̇o2 ratio. This suggests that the PE-induced acceleration in oxidative metabolism in T2D is a result of greater O2 extraction and better matching between O2 delivery and utilization.
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Affiliation(s)
- Joel Rocha
- Division of Sport and Exercise Sciences, Abertay University, Dundee, United Kingdom
| | - Norita Gildea
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Donal O’Shea
- Department of Endocrinology, St. Columcille’s Hospital, Dublin, Ireland
- Department of Endocrinology and Diabetes Mellitus, St. Vincent’s University Hospital, Dublin, Ireland
| | - Simon Green
- School of Science and Health, Western Sydney University, Sydney, New South Wales, Australia
| | - Mikel Egaña
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
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Lewis MT, Kasper JD, Bazil JN, Frisbee JC, Wiseman RW. Skeletal muscle energetics are compromised only during high-intensity contractions in the Goto-Kakizaki rat model of type 2 diabetes. Am J Physiol Regul Integr Comp Physiol 2019; 317:R356-R368. [PMID: 31188651 PMCID: PMC6732426 DOI: 10.1152/ajpregu.00127.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 06/07/2019] [Accepted: 06/07/2019] [Indexed: 12/24/2022]
Abstract
Type 2 diabetes (T2D) presents with hyperglycemia and insulin resistance, affecting over 30 million people in the United States alone. Previous work has hypothesized that mitochondria are dysfunctional in T2D and results in both reduced ATP production and glucose disposal. However, a direct link between mitochondrial function and T2D has not been determined. In the current study, the Goto-Kakizaki (GK) rat model of T2D was used to quantify mitochondrial function in vitro and in vivo over a broad range of contraction-induced metabolic workloads. During high-frequency sciatic nerve stimulation, hindlimb muscle contractions at 2- and 4-Hz intensities, the GK rat failed to maintain similar bioenergetic steady states to Wistar control (WC) rats measured by phosphorus magnetic resonance spectroscopy, despite similar force production. Differences were not due to changes in mitochondrial content in red (RG) or white gastrocnemius (WG) muscles (cytochrome c oxidase, RG: 22.2 ± 1.6 vs. 23.3 ± 1.7 U/g wet wt; WG: 10.8 ± 1.1 vs. 12.1 ± 0.9 U/g wet wt; GK vs. WC, respectively). Mitochondria isolated from muscles of GK and WC rats also showed no difference in mitochondrial ATP production capacity in vitro, measured by high-resolution respirometry. At lower intensities (0.25-1 Hz) there were no detectable differences between GK and WC rats in sustained energy balance. There were similar phosphocreatine concentrations during steady-state contraction and postcontractile recovery (τ = 72 ± 6 s GK versus 71 ± 2 s WC). Taken together, these results suggest that deficiencies in skeletal muscle energetics seen at higher intensities are not due to mitochondrial dysfunction in the GK rat.
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Affiliation(s)
- Matthew T Lewis
- Department of Physiology, Michigan State University, East Lansing, Michigan
| | - Jonathan D Kasper
- Department of Physiology, Michigan State University, East Lansing, Michigan
| | - Jason N Bazil
- Department of Physiology, Michigan State University, East Lansing, Michigan
| | - Jefferson C Frisbee
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Robert W Wiseman
- Department of Physiology, Michigan State University, East Lansing, Michigan
- Department of Radiology, Michigan State University, East Lansing, Michigan
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22
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Porcelli S, Grassi B, Poole DC, Marzorati M. Exercise intolerance in patients with mitochondrial myopathies: perfusive and diffusive limitations in the O2 pathway. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2019.05.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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23
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Gildea N, Rocha J, McDermott A, O'Shea D, Green S, Egaña M. Influence of type 2 diabetes on muscle deoxygenation during ramp incremental cycle exercise. Respir Physiol Neurobiol 2019; 269:103258. [PMID: 31349019 DOI: 10.1016/j.resp.2019.103258] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 07/04/2019] [Accepted: 07/23/2019] [Indexed: 11/18/2022]
Abstract
We tested the hypothesis that type 2 diabetes (T2D) alters the profile of muscle fractional oxygen (O2) extraction (near-infrared spectroscopy) during incremental cycle exercise. Seventeen middle-aged individuals with uncomplicated T2D and 17 controls performed an upright ramp test to exhaustion. The rate of muscle deoxygenation (i.e. deoxygenated haemoglobin and myoglobin concentration, Δ[HHb+Mb]) profiles of the vastus lateralis muscle were normalised to 100% of the response, plotted against % power output (PO) and fitted with a double linear regression model. Peak oxygen uptake was significantly (P < 0.05) reduced in individuals with T2D. The %Δ[HHb+Mb]/%PO slope of the first linear segment of the double linear regression function was significantly (P < 0.05) steeper in T2D than controls (1.59 (1.14) vs 1.23 (0.51)). Both groups displayed a near-plateau in Δ[HHb+Mb] at an exercise intensity (%PO) not different amongst them. Such findings suggest that a reduced O2 delivery to active muscles is an important underlying cause of exercise intolerance during a maximum graded test in middle-aged individuals with T2D.
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Affiliation(s)
- Norita Gildea
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Joel Rocha
- Division of Sport and Exercise Sciences, Abertay University, Dundee, UK
| | - Adam McDermott
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Donal O'Shea
- Endocrinology, St Columcille's and St Vincent's Hospitals, Dublin, Ireland
| | - Simon Green
- School of Science and Health, Western Sydney University, Sydney, Australia
| | - Mikel Egaña
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland.
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24
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Poole DC. Edward F. Adolph Distinguished Lecture. Contemporary model of muscle microcirculation: gateway to function and dysfunction. J Appl Physiol (1985) 2019; 127:1012-1033. [PMID: 31095460 DOI: 10.1152/japplphysiol.00013.2019] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
This review strikes at the very heart of how the microcirculation functions to facilitate blood-tissue oxygen, substrate, and metabolite fluxes in skeletal muscle. Contemporary evidence, marshalled from animals and humans using the latest techniques, challenges iconic perspectives that have changed little over the past century. Those perspectives include the following: the presence of contractile or collapsible capillaries in muscle, unitary control by precapillary sphincters, capillary recruitment at the onset of contractions, and the notion of capillary-to-mitochondrial diffusion distances as limiting O2 delivery. Today a wealth of physiological, morphological, and intravital microscopy evidence presents a completely different picture of microcirculatory control. Specifically, capillary red blood cell (RBC) and plasma flux is controlled primarily at the arteriolar level with most capillaries, in healthy muscle, supporting at least some flow at rest. In healthy skeletal muscle, this permits substrate access (whether carried in RBCs or plasma) to a prodigious total capillary surface area. Pathologies such as heart failure or diabetes decrease access to that exchange surface by reducing the proportion of flowing capillaries at rest and during exercise. Capillary morphology and function vary disparately among tissues. The contemporary model of capillary function explains how, following the onset of exercise, muscle O2 uptake kinetics can be extremely fast in health but slowed in heart failure and diabetes impairing contractile function and exercise tolerance. It is argued that adoption of this model is fundamental for understanding microvascular function and dysfunction and, as such, to the design and evaluation of effective therapeutic strategies to improve exercise tolerance and decrease morbidity and mortality in disease.
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Affiliation(s)
- David C Poole
- Departments of Kinesiology, Anatomy and Physiology, Kansas State University, Manhattan, Kansas
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25
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Gardner AW, Montgomery PS, Wang M, Chen C, Kuroki M, Kim DJK. Vascular Inflammation, Calf Muscle Oxygen Saturation, and Blood Glucose are Associated With Exercise Pressor Response in Symptomatic Peripheral Artery Disease. Angiology 2019; 70:747-755. [DOI: 10.1177/0003319719838399] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We determined whether calf muscle oxygen saturation (StO2) and vascular biomarkers of inflammation and oxidative stress were associated with an exercise pressor response during treadmill walking in 179 patients with symptomatic peripheral artery disease (PAD). The exercise pressor response was measured as the change in blood pressure from rest to the end of the first 2-minute treadmill stage (2 mph, 0% grade). There was a wide range in the change in systolic blood pressure (−46 to 50 mm Hg) and in diastolic blood pressure (−23 to 38 mm Hg), with mean increases of 4.3 and 1.4 mm Hg, respectively. In multiple regression analyses, significant predictors of systolic pressure included glucose ( P < .001) and insulin ( P = .039). Significant predictors of diastolic pressure included cultured endothelial cell apoptosis ( P = .019), the percentage drop in exercise calf muscle (StO2; P = .023), high-sensitivity C-reactive protein ( P = .032), and glucose ( P = .033). Higher levels in pro-inflammatory vascular biomarkers, impaired calf muscle StO2 during exercise, and elevated blood glucose were independently associated with greater exercise pressor response in patients with symptomatic PAD. The clinical implication is that exercise and nutritional interventions designed to improve inflammation, microcirculation, and glucose metabolism may also lower blood pressure during exercise in patients with symptomatic PAD.
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Affiliation(s)
- Andrew W. Gardner
- Department of Physical Medicine and Rehabilitation, Penn State College of Medicine, Hershey, PA, USA
| | - Polly S. Montgomery
- Department of Physical Medicine and Rehabilitation, Penn State College of Medicine, Hershey, PA, USA
| | - Ming Wang
- Department of Public Health Sciences, Penn State College of Medicine, Hershey, PA, USA
| | - Chixiang Chen
- Department of Public Health Sciences, Penn State College of Medicine, Hershey, PA, USA
| | - Marcos Kuroki
- Heart and Vascular Institute, Penn State College of Medicine, Hershey, PA, USA
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26
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Obesity and inactivity, not hyperglycemia, cause exercise intolerance in individuals with type 2 diabetes: Solving the obesity and inactivity versus hyperglycemia causality dilemma. Med Hypotheses 2019; 123:110-114. [DOI: 10.1016/j.mehy.2019.01.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 01/15/2019] [Indexed: 12/29/2022]
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27
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Frisbee JC, Lewis MT, Kasper JD, Chantler PD, Wiseman RW. Type 2 diabetes mellitus in the Goto-Kakizaki rat impairs microvascular function and contributes to premature skeletal muscle fatigue. J Appl Physiol (1985) 2018; 126:626-637. [PMID: 30571284 DOI: 10.1152/japplphysiol.00751.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Despite extensive investigation into the impact of metabolic disease on vascular function and, by extension, tissue perfusion and organ function, interpreting results for specific risk factors can be complicated by the additional risks present in most models. To specifically determine the impact of type 2 diabetes without obesity on skeletal muscle microvascular structure/function and on active hyperemia with elevated metabolic demand, we used 17-wk-old Goto-Kakizaki (GK) rats to study microvascular function at multiple levels of resolution. Gracilis muscle arterioles demonstrated blunted dilation to acetylcholine (both ex vivo proximal and in situ distal arterioles) and elevated shear (distal arterioles only). All other alterations to reactivity appeared to reflect compromised endothelial function associated with increased thromboxane (Tx)A2 production and oxidant stress/inflammation rather than alterations to vascular smooth muscle function. Structural changes to the microcirculation of GK rats were confined to reduced microvessel density of ~12%, with no evidence for altered vascular wall mechanics. Active hyperemia with either field stimulation of in situ cremaster muscle or electrical stimulation via the sciatic nerve for in situ gastrocnemius muscle was blunted in GK rats, primarily because of blunted functional dilation of skeletal muscle arterioles. The blunted active hyperemia was associated with impaired oxygen uptake (V̇o2) across the muscle and accelerated muscle fatigue. Acute interventions to reduce oxidant stress (TEMPOL) and TxA2 action (SQ-29548) or production (dazmegrel) improved muscle perfusion, V̇o2, and muscle performance. These results suggest that type 2 diabetes mellitus in GK rats impairs skeletal muscle arteriolar function apparently early in the progression of the disease and potentially via an increased reactive oxygen species/inflammation-induced TxA2 production/action on network function as a major contributing mechanism. NEW & NOTEWORTHY The impact of type 2 diabetes mellitus on vascular structure/function remains an area lacking clarity. Using diabetic Goto-Kakizaki rats before the development of other risk factors, we determined alterations to vascular structure/function and skeletal muscle active hyperemia. Type 2 diabetes mellitus reduced arteriolar endothelium-dependent dilation associated with increased thromboxane A2 generation. Although modest microvascular rarefaction was evident, there were no other alterations to vascular structure/function. Skeletal muscle active hyperemia was blunted, although it improved after antioxidant or anti-thromboxane A2 treatment.
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Affiliation(s)
- Jefferson C Frisbee
- Department of Medical Biophysics, Western University , London, Ontario , Canada
| | - Matthew T Lewis
- Department of Physiology, Michigan State University , East Lansing, Michigan
| | - Jonathan D Kasper
- Department of Physiology, Michigan State University , East Lansing, Michigan
| | - Paul D Chantler
- Division of Exercise Physiology, West Virginia University , Morgantown, West Virginia
| | - Robert W Wiseman
- Department of Physiology, Michigan State University , East Lansing, Michigan.,Department of Radiology, Michigan State University , East Lansing, Michigan
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28
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Hirai DM, Colburn TD, Craig JC, Hotta K, Kano Y, Musch TI, Poole DC. Skeletal muscle interstitial O 2 pressures: bridging the gap between the capillary and myocyte. Microcirculation 2018; 26:e12497. [PMID: 30120845 DOI: 10.1111/micc.12497] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 07/26/2018] [Accepted: 08/13/2018] [Indexed: 01/18/2023]
Abstract
The oxygen transport pathway from air to mitochondria involves a series of transfer steps within closely integrated systems (pulmonary, cardiovascular, and tissue metabolic). Small and finite O2 stores in most mammalian species require exquisitely controlled changes in O2 flux rates to support elevated ATP turnover. This is especially true for the contracting skeletal muscle where O2 requirements may increase two orders of magnitude above rest. This brief review focuses on the mechanistic bases for increased microvascular blood-myocyte O2 flux (V̇O2 ) from rest to contractions. Fick's law dictates that V̇O2 elevations driven by muscle contractions are produced by commensurate changes in driving force (ie, O2 pressure gradients; ΔPO2 ) and/or effective diffusing capacity (DO2 ). While previous evidence indicates that increased DO2 helps modulate contracting muscle O2 flux, up until recently the role of the dynamic ΔPO2 across the capillary wall was unknown. Recent phosphorescence quenching investigations of both microvascular and novel interstitial PO2 kinetics in health have resolved an important step in the O2 cascade between the capillary and myocyte. Specifically, the significant transmural ΔPO2 at rest was sustained (but not increased) during submaximal contractions. This supports the contention that the blood-myocyte interface provides a substantial effective resistance to O2 diffusion and underscores that modulations in erythrocyte hemodynamics and distribution (DO2 ) are crucial to preserve the driving force for O2 flux across the capillary wall (ΔPO2 ) during contractions. Investigation of the O2 transport pathway close to muscle mitochondria is key to identifying disease mechanisms and develop therapeutic approaches to ameliorate dysfunction and exercise intolerance.
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Affiliation(s)
- Daniel M Hirai
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
| | - Trenton D Colburn
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
| | - Jesse C Craig
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
| | - Kazuki Hotta
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - Yutaka Kano
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - Timothy I Musch
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
| | - David C Poole
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
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29
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de Lima LAP, Raison M, Achiche S, de Lucas RD. Second order modeling for the pulmonary oxygen uptake on-kinetics: a comprehensive solution for overshooting and non-overshooting responses to exercise. J Appl Physiol (1985) 2018; 125:1315-1328. [PMID: 29901434 DOI: 10.1152/japplphysiol.00147.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The human oxygen uptake (VO2) response to step-like increases in work rate is currently modeled by a First Order System Multi-Exponential (FOME) arrangement. Due to their first order nature, none of FOME model's exponentials is able to model an overshoot in the oxygen uptake kinetics (OVO2K). Nevertheless, OVO2K phenomena are observed in the fundamental component of trained individuals' step responses. We hypothesized that a Mixed Multi-Exponential (MiME) model, where the fundamental component is modeled with a second instead of a first order system, would present a better overall performance than that of the traditional FOME model in fitting VO2 on-kinetics at all work rates, either presenting or not OVO2K. Fourteen well-trained male cyclists performed three step on-transitions at each of three work rates below their individual lactate thresholds' work rate (WRLT), and two step on-transitions at each of two exercise intensities above WRLT. Averaged responses for each WR were fitted with MiME and FOME models. Root mean standard errors were used for comparisons between fitting performances. Additionally, a methodology for detecting and quantifying OVO2K phenomena is proposed. Second order solutions performed better (p<0.000) than the first order exponential when the OVO2K was present, and did not differ statistically (p=0.973) in its absence. OVO2K occurrences were observed below and, for the first time, above WRLT (88 and 7%, respectively). We concluded that the MiME model is more adequate and comprehensive than the FOME model in explaining VO2 step on-transient responses, considering cases with or without OVO2K altogether.
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Affiliation(s)
| | - Maxime Raison
- Mechanical Engineering, Polytechinque Montreal, Canada
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30
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Jalil B, Hartwig V, Salvetti O, Potì L, Gargani L, Barskova T, Matucci Cerinic M, L'Abbate A. Assessment of hand superficial oxygenation during ischemia/reperfusion in healthy subjects versus systemic sclerosis patients by 2D near infrared spectroscopic imaging. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2018; 155:101-108. [PMID: 29512489 DOI: 10.1016/j.cmpb.2017.12.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 11/03/2017] [Accepted: 12/11/2017] [Indexed: 06/08/2023]
Abstract
BACKGROUND AND OBJECTIVE Patients affected by systemic sclerosis (SSc) develop functional and structural microcirculatory dysfunction, which progressively evolves towards systemic tissue fibrosis (sclerosis). Disease initially affects distal extremities, which become preferential sites of diagnostic scrutiny. This pilot investigation tested the hypothesis that peripheral microcirculatory dysfunction in SSc could be non-invasively assessed by 2D Near Infrared Spectroscopic (NIRS) imaging of the hand associated with Vascular Occlusion Testing (VOT). NIRS allows measurement of hemoglobin oxygen saturation (StO2) in the blood perfusing the volume tissue under scrutiny. METHODS In five normal volunteers and five SSc patients we applied a multispectral oximetry imaging device (Kent camera, Kent Imaging, Calgary, Canada) to acquire StO2 2D maps of the whole hand palm during baseline, ischemia and reperfusion phase. RESULTS We found significant differences between controls and SSc patients in basal StO2 (82.80 ± 2.51 vs 65.44 ± 7.96%, p = 0.0016), minimum StO2 (59.35 ± 4.29 vs 40.73 ± 6.47%, p = 0.0007), final StO2 (83.83 ± 4.09 vs 68.84 ± 11.41%, p = 0.02) and time to maximum StO2 (40 ± 12.25 vs 62 ± 4.47 s, p = 0.005). CONCLUSIONS This is, to our knowledge, the first application of 2D NIRS imaging of the whole hand to the investigation of microvascular dysfunction in systemic sclerosis. The image processing presented here considered the StO2 in the entire hand allowing a comprehensive view of the spatial heterogeneity of microvascular dysfunction.
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Affiliation(s)
- Bushra Jalil
- Istituto di Scienza e Tecnologie dell'Informazione "Alessandro Faedo" CNR, Via Moruzzi 1, 56124 Pisa, Italy
| | - Valentina Hartwig
- Institute of Clinical Physiology, Italian National Research Council (CNR), Via Moruzzi 1, 56124 Pisa, Italy.
| | - Ovidio Salvetti
- Istituto di Scienza e Tecnologie dell'Informazione "Alessandro Faedo" CNR, Via Moruzzi 1, 56124 Pisa, Italy
| | - Luca Potì
- Consorzio Nazionale Interuniversitario per le Telecomunicazioni, Pisa, Italy
| | - Luna Gargani
- Institute of Clinical Physiology, Italian National Research Council (CNR), Via Moruzzi 1, 56124 Pisa, Italy
| | - Tatiana Barskova
- Department of Experimental and Clinical Medicine, Division of Rheumatology AOUC, University of Florence, Florence, Italy
| | - Marco Matucci Cerinic
- Department of Experimental and Clinical Medicine, Division of Rheumatology AOUC, University of Florence, Florence, Italy
| | - A L'Abbate
- Institute of Clinical Physiology, Italian National Research Council (CNR), Via Moruzzi 1, 56124 Pisa, Italy; Scuola Superiore Sant'Anna, Institute of Life Sciences, Piazza Martiri della Libertà 33, 56127 Pisa, Italy
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31
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Macia M, Pecchi E, Desrois M, Lan C, Vilmen C, Portha B, Bernard M, Bendahan D, Giannesini B. Exercise training impacts exercise tolerance and bioenergetics in gastrocnemius muscle of non-obese type-2 diabetic Goto-Kakizaki rat in vivo. Biochimie 2018; 148:36-45. [PMID: 29499298 DOI: 10.1016/j.biochi.2018.02.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 02/23/2018] [Indexed: 12/18/2022]
Abstract
The functional and bioenergetics impact of regular physical activity upon type-2 diabetic skeletal muscle independently of confounding factors of overweight remains undocumented. Here, gastrocnemius muscle energy fluxes, mitochondrial capacity and mechanical performance were assessed noninvasively and longitudinally in non-obese diabetic Goto-Kakizaki rats using magnetic resonance (MR) imaging and dynamic 31-phosphorus MR spectroscopy (31P-MRS) throughout a 6-min fatiguing bout of exercise performed before, in the middle (4-week) and at the end of an 8-week training protocol consisting in 60-min daily run on a treadmill. The training protocol reduced plasmatic insulin level (-61%) whereas blood glucose and non-esterified fatty acids levels remained unaffected, thereby indicating an improvement of insulin sensitivity. It also increased muscle mitochondrial citrate synthase activity (+45%) but this increase did not enhance oxidative ATP synthesis capacity in working muscle in vivo while glycolytic ATP production was increased (+33%). On the other hand, the training protocol impaired maximal force-generating capacity (-9%), total amount of force produced (-12%) and increased ATP cost of contraction (+32%) during the fatiguing exercise. Importantly, these deleterious effects were transiently worsened in the middle of the 8-week period, in association with reduced oxidative capacity and increased basal [Pi]/[PCr] ratio (an in vivo biomarker of muscle damage). These data demonstrate that the beneficial effect of regular training on insulin sensitivity in non-obese diabetic rat occurs separately from any improvement in muscle mitochondrial function and might be linked to an increased capacity for metabolizing glucose through anaerobic process in exercising muscle.
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Affiliation(s)
| | | | | | - Carole Lan
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France
| | | | - Bernard Portha
- Université Paris-Diderot, Sorbonne Paris Cité, Laboratoire B2PE, Unité BFA, CNRS EAC 4413, Paris, France
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32
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Poitras VJ, Hudson RW, Tschakovsky ME. Exercise intolerance in Type 2 diabetes: is there a cardiovascular contribution? J Appl Physiol (1985) 2018; 124:1117-1139. [PMID: 29420147 DOI: 10.1152/japplphysiol.00070.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Physical activity is critically important for Type 2 diabetes management, yet adherence levels are poor. This might be partly due to disproportionate exercise intolerance. Submaximal exercise tolerance is highly sensitive to muscle oxygenation; impairments in exercising muscle oxygen delivery may contribute to exercise intolerance in Type 2 diabetes since there is considerable evidence for the existence of both cardiac and peripheral vascular dysfunction. While uncompromised cardiac output during submaximal exercise is consistently observed in Type 2 diabetes, it remains to be determined whether an elevated cardiac sympathetic afferent reflex could sympathetically restrain exercising muscle blood flow. Furthermore, while deficits in endothelial function are common in Type 2 diabetes and are often cited as impairing exercising muscle oxygen delivery, no direct evidence in exercise exists, and there are several other vasoregulatory mechanisms whose dysfunction could contribute. Finally, while there are findings of impaired oxygen delivery, conflicting evidence also exists. A definitive conclusion that Type 2 diabetes compromises exercising muscle oxygen delivery remains premature. We review these potentially dysfunctional mechanisms in terms of how they could impair oxygen delivery in exercise, evaluate the current literature on whether an oxygen delivery deficit is actually manifest, and correspondingly identify key directions for future research.
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Affiliation(s)
- Veronica J Poitras
- School of Kinesiology and Health Studies, Queen's University , Kingston, Ontario , Canada.,Department of Physiology, Queen's University , Kingston, Ontario , Canada.,Children's Hospital of Eastern Ontario, Research Institute , Ottawa, Ontario , Canada
| | - Robert W Hudson
- Department of Medicine, Division of Endocrinology, Queen's University , Kingston, Ontario , Canada
| | - Michael E Tschakovsky
- School of Kinesiology and Health Studies, Queen's University , Kingston, Ontario , Canada
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Woessner MN, McIlvenna LC, Ortiz de Zevallos J, Neil CJ, Allen JD. Dietary nitrate supplementation in cardiovascular health: an ergogenic aid or exercise therapeutic? Am J Physiol Heart Circ Physiol 2018; 314:H195-H212. [DOI: 10.1152/ajpheart.00414.2017] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Oral consumption of inorganic nitrate, which is abundant in green leafy vegetables and roots, has been shown to increase circulating plasma nitrite concentration, which can be converted to nitric oxide in low oxygen conditions. The associated beneficial physiological effects include a reduction in blood pressure, modification of platelet aggregation, and increases in limb blood flow. There have been numerous studies of nitrate supplementation in healthy recreational and competitive athletes; however, the ergogenic benefits are currently unclear due to a variety of factors including small sample sizes, different dosing regimens, variable nitrate conversion rates, the heterogeneity of participants’ initial fitness levels, and the types of exercise tests used. In clinical populations, the study results seem more promising, particularly in patients with cardiovascular diseases who typically present with disruptions in the ability to transport oxygen from the atmosphere to working tissues and reduced exercise tolerance. Many of these disease-related, physiological maladaptations, including endothelial dysfunction, increased reactive oxygen species, reduced tissue perfusion, and muscle mitochondrial dysfunction, have been previously identified as potential targets for nitric oxide restorative effects. This review is the first of its kind to outline the current evidence for inorganic nitrate supplementation as a therapeutic intervention to restore exercise tolerance and improve quality of life in patients with cardiovascular diseases. We summarize the factors that appear to limit or maximize its effectiveness and present a case for why it may be more effective in patients with cardiovascular disease than as ergogenic aid in healthy populations.
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Affiliation(s)
- Mary N. Woessner
- Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Victoria, Australia
- Western Health, Melbourne, Victoria, Australia
| | - Luke C. McIlvenna
- Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Victoria, Australia
| | - Joaquin Ortiz de Zevallos
- Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Victoria, Australia
- Department of Kinesiology, University of Virginia, Charlottesville, Virginia
| | - Christopher J. Neil
- Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Victoria, Australia
- Western Health, Melbourne, Victoria, Australia
| | - Jason D. Allen
- Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Victoria, Australia
- Western Health, Melbourne, Victoria, Australia
- Department of Kinesiology, University of Virginia, Charlottesville, Virginia
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Hirai DM, Craig JC, Colburn TD, Eshima H, Kano Y, Sexton WL, Musch TI, Poole DC. Skeletal muscle microvascular and interstitial PO2 from rest to contractions. J Physiol 2018; 596:869-883. [PMID: 29288568 DOI: 10.1113/jp275170] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 12/01/2017] [Indexed: 01/21/2023] Open
Abstract
KEY POINTS Oxygen pressure gradients across the microvascular walls are essential for oxygen diffusion from blood to tissue cells. At any given flux, the magnitude of these transmural gradients is proportional to the local resistance. The greatest resistance to oxygen transport into skeletal muscle is considered to reside in the short distance between red blood cells and myocytes. Although crucial to oxygen transport, little is known about transmural pressure gradients within skeletal muscle during contractions. We evaluated oxygen pressures within both the skeletal muscle microvascular and interstitial spaces to determine transmural gradients during the rest-contraction transient in anaesthetized rats. The significant transmural gradient observed at rest was sustained during submaximal muscle contractions. Our findings support that the blood-myocyte interface provides substantial resistance to oxygen diffusion at rest and during contractions and suggest that modulations in microvascular haemodynamics and red blood cell distribution constitute primary mechanisms driving increased transmural oxygen flux with contractions. ABSTRACT Oxygen pressure (PO2) gradients across the blood-myocyte interface are required for diffusive O2 transport, thereby supporting oxidative metabolism. The greatest resistance to O2 flux into skeletal muscle is considered to reside between the erythrocyte surface and adjacent sarcolemma, although this has not been measured during contractions. We tested the hypothesis that O2 gradients between skeletal muscle microvascular (PO2 mv ) and interstitial (PO2 is ) spaces would be present at rest and maintained or increased during contractions. PO2 mv and PO2 is were determined via phosphorescence quenching (Oxyphor probes G2 and G4, respectively) in the exposed rat spinotrapezius during the rest-contraction transient (1 Hz, 6 V; n = 8). PO2 mv was higher than PO2 is in all instances from rest (34.9 ± 6.0 versus 15.7 ± 6.4) to contractions (28.4 ± 5.3 versus 10.6 ± 5.2 mmHg, respectively) such that the mean PO2 gradient throughout the transient was 16.9 ± 6.6 mmHg (P < 0.05 for all). No differences in the amplitude of PO2 fall with contractions were observed between the microvasculature and interstitium (10.9 ± 2.3 versus 9.0 ± 3.5 mmHg, respectively; P > 0.05). However, the speed of the PO2 is fall during contractions was slower than that of PO2 mv (time constant: 12.8 ± 4.7 versus 9.0 ± 5.1 s, respectively; P < 0.05). Consistent with our hypothesis, a significant transmural gradient was sustained (but not increased) from rest to contractions. This supports that the blood-myocyte interface is the site of a substantial PO2 gradient driving O2 diffusion during metabolic transients. Based on Fick's law, elevated O2 flux with contractions must thus rely primarily on modulations in effective diffusing capacity (mainly erythrocyte haemodynamics and distribution) as the PO2 gradient is not increased.
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Affiliation(s)
- Daniel M Hirai
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Jesse C Craig
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Trenton D Colburn
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Hiroaki Eshima
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - Yutaka Kano
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - William L Sexton
- Department of Physiology, A.T. Still University of Health Sciences, Kirksville, MO, USA
| | - Timothy I Musch
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - David C Poole
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
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Kuwabara WMT, Panveloski-Costa AC, Yokota CNF, Pereira JNB, Filho JM, Torres RP, Hirabara SM, Curi R, Alba-Loureiro TC. Comparison of Goto-Kakizaki rats and high fat diet-induced obese rats: Are they reliable models to study Type 2 Diabetes mellitus? PLoS One 2017; 12:e0189622. [PMID: 29220408 PMCID: PMC5722336 DOI: 10.1371/journal.pone.0189622] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 11/29/2017] [Indexed: 02/07/2023] Open
Abstract
Type 2 Diabetes mellitus (T2DM) is an evident growing disease that affects different cultures throughout the world. T2DM occurs under the influence of three main factors: the genetic background, environmental and behavioral components. Obesity is strongly associated to the development of T2DM in the occident, while in the orient most of the diabetic patients are considered lean. Genetics may be a key factor in the development of T2DM in societies where obesity is not a recurrent public health problem. Herein, two different models of rats were used to understand their differences and reliability as experimental models to study the pathophysiology of T2DM, in two different approaches: the genetic (GK rats) and the environmental (HFD-induced obese rats) influences. GK rats were resistant to weight gain even though food/energy consumption (relative to body weight) was higher in this group. HFD, on the other hand, induced obesity in Wistar rats. White adipose tissue (WAT) expansion in this group was accompanied by immune cells infiltration, inflammation and insulin resistance. GK rats also presented WAT inflammation and insulin resistance; however, no immune cells infiltration was observed in the WAT of this group. Liver of HFD group presented fat accumulation without differences in inflammatory cytokines content, while liver of GK rats didn't present fat accumulation, but showed an increase of IL-6 and IL-10 content and glycogen. Also, GK rats showed increased plasma GOT and GPT. Soleus muscle of HFD presented normal insulin signaling, contrary to GK rats, which presented higher content of basal phosphorylation of GSK-3β. Our results demonstrated that HFD developed a mild insulin resistance in Wistar rats, but was not sufficient to develop T2DM. In contrast, GK rats presented all the typical hallmarks of T2DM, such as insulin resistance, defective insulin production, fasting hyperglycemia/hyperinsulinemia and lipid plasma alteration. Thus, on the given time point of this study, we may conclude that only GK rats shown to be a reliable model to study T2DM.
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Affiliation(s)
| | - Ana Carolina Panveloski-Costa
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | | | - Joice Naiara Bertaglia Pereira
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- Cruzeiro do Sul University, São Paulo, Brazil
| | - Jorge Mancini Filho
- Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | | | | | - Rui Curi
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- Cruzeiro do Sul University, São Paulo, Brazil
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Liu Y, Mei X, Li J, Lai N, Yu X. Mitochondrial function assessed by 31P MRS and BOLD MRI in non-obese type 2 diabetic rats. Physiol Rep 2017; 4:4/15/e12890. [PMID: 27511984 PMCID: PMC4985553 DOI: 10.14814/phy2.12890] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 07/19/2016] [Indexed: 12/23/2022] Open
Abstract
The study aims to characterize age‐associated changes in skeletal muscle bioenergetics by evaluating the response to ischemia‐reperfusion in the skeletal muscle of the Goto‐Kakizaki (GK) rats, a rat model of non‐obese type 2 diabetes (T2D). 31P magnetic resonance spectroscopy (MRS) and blood oxygen level‐dependent (BOLD) MRI was performed on the hindlimb of young (12 weeks) and adult (20 weeks) GK and Wistar (control) rats. 31P‐MRS and BOLD‐MRI data were acquired continuously during an ischemia and reperfusion protocol to quantify changes in phosphate metabolites and muscle oxygenation. The time constant of phosphocreatine recovery, an index of mitochondrial oxidative capacity, was not statistically different between GK rats (60.8 ± 13.9 sec in young group, 83.7 ± 13.0 sec in adult group) and their age‐matched controls (62.4 ± 11.6 sec in young group, 77.5 ± 7.1 sec in adult group). During ischemia, baseline‐normalized BOLD‐MRI signal was significantly lower in GK rats than in their age‐matched controls. These results suggest that insulin resistance leads to alterations in tissue metabolism without impaired mitochondrial oxidative capacity in GK rats.
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Affiliation(s)
- Yuchi Liu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio Case Center for Imaging Research, Case Western Reserve University, Cleveland, Ohio
| | - Xunbai Mei
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio Case Center for Imaging Research, Case Western Reserve University, Cleveland, Ohio
| | - Jielei Li
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
| | - Nicola Lai
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio Department of Electrical and Computer Engineering and Biomedical Engineering Institute, Old Dominion University, Norfolk, Virginia
| | - Xin Yu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio Case Center for Imaging Research, Case Western Reserve University, Cleveland, Ohio Department of Radiology, Case Western Reserve University, Cleveland, Ohio Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio
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Vascular K ATP channels mitigate severe muscle O 2 delivery-utilization mismatch during contractions in chronic heart failure rats. Respir Physiol Neurobiol 2017; 238:33-40. [PMID: 28119150 DOI: 10.1016/j.resp.2017.01.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 01/10/2017] [Accepted: 01/18/2017] [Indexed: 12/14/2022]
Abstract
The vascular ATP-sensitive K+ (KATP) channel is a mediator of skeletal muscle microvascular oxygenation (PO2mv) during contractions in health. We tested the hypothesis that KATP channel function is preserved in chronic heart failure (CHF) and therefore its inhibition would reduce PO2mv and exacerbate the time taken to reach the PO2mv steady-state during contractions of the spinotrapezius muscle. Moreover, we hypothesized that subsequent KATP channel activation would oppose the effects of this inhibition. Muscle PO2mv (phosphorescence quenching) was measured during 180s of 1-Hz twitch contractions (∼6V) under control, glibenclamide (GLI, KATP channel antagonist; 5mg/kg) and pinacidil (PIN, KATP channel agonist; 5mg/kg) conditions in 16 male Sprague-Dawley rats with CHF induced via myocardial infarction (coronary artery ligation, left ventricular end-diastolic pressure: 18±1mmHg). GLI reduced baseline PO2mv (control: 28.3±0.9, GLI: 24.8±1.0mmHg, p<0.05), lowered mean PO2mv (average PO2mv during the overall time taken to reach the steady-state; control: 20.6±0.6, GLI: 17.6±0.3mmHg, p<0.05), and slowed the attainment of steady-state PO2mv (overall mean response time; control: 66.1±10.2, GLI: 93.6±7.8s, p<0.05). PIN opposed these effects on the baseline PO2mv, mean PO2mv and time to reach the steady-state PO2mv (p<0.05 for all vs. GLI). Inhibition of KATP channels exacerbates the transient mismatch between muscle O2 delivery and utilization in CHF rats and this effect is opposed by PIN. These data reveal that the KATP channel constitutes one of the select few well-preserved mechanisms of skeletal muscle microvascular oxygenation control in CHF.
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Niemeijer VM, Spee RF, Schoots T, Wijn PFF, Kemps HMC. Limitations of skeletal muscle oxygen delivery and utilization during moderate-intensity exercise in moderately impaired patients with chronic heart failure. Am J Physiol Heart Circ Physiol 2016; 311:H1530-H1539. [DOI: 10.1152/ajpheart.00474.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 09/28/2016] [Indexed: 11/22/2022]
Abstract
The extent and speed of transient skeletal muscle deoxygenation during exercise onset in patients with chronic heart failure (CHF) are related to impairments of local O2 delivery and utilization. This study examined the physiological background of submaximal exercise performance in 19 moderately impaired patients with CHF (Weber class A, B, and C) compared with 19 matched healthy control (HC) subjects by measuring skeletal muscle oxygenation (SmO2) changes during cycling exercise. All subjects performed two subsequent moderate-intensity 6-min exercise tests (bouts 1 and 2) with measurements of pulmonary oxygen uptake kinetics and SmO2 using near-infrared spatially resolved spectroscopy at the vastus lateralis for determination of absolute oxygenation values, amplitudes, kinetics (mean response time for onset), and deoxygenation overshoot characteristics. In CHF, deoxygenation kinetics were slower compared with HC (21.3 ± 5.3 s vs. 16.7 ± 4.4 s, P < 0.05, respectively). After priming exercise (i.e., during bout 2), deoxygenation kinetics were accelerated in CHF to values no longer different from HC (16.9 ± 4.6 s vs. 15.4 ± 4.2 s, P = 0.35). However, priming did not speed deoxygenation kinetics in CHF subjects with a deoxygenation overshoot, whereas it did reduce the incidence of the overshoot in this specific group ( P < 0.05). These results provide evidence for heterogeneity with respect to limitations of O2 delivery and utilization during moderate-intensity exercise in patients with CHF, with slowed deoxygenation kinetics indicating a predominant O2 utilization impairment and the presence of a deoxygenation overshoot, with a reduction after priming in a subgroup, indicating an initial O2 delivery to utilization mismatch.
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Affiliation(s)
- Victor M. Niemeijer
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven, the Netherlands; and
| | - Ruud F. Spee
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
| | - Thijs Schoots
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
| | - Pieter F. F. Wijn
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven, the Netherlands; and
- Department of Medical Physics, Máxima Medical Centre, Veldhoven, the Netherlands
| | - Hareld M. C. Kemps
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
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Holdsworth CT, Ferguson SK, Poole DC, Musch TI. Modulation of rat skeletal muscle microvascular O2 pressure via KATP channel inhibition following the onset of contractions. Respir Physiol Neurobiol 2016; 222:48-54. [DOI: 10.1016/j.resp.2015.11.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/16/2015] [Accepted: 11/14/2015] [Indexed: 11/26/2022]
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Yamakoshi K, Yagishita K, Tsuchimochi H, Inagaki T, Shirai M, Poole DC, Kano Y. Microvascular oxygen partial pressure during hyperbaric oxygen in diabetic rat skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2015; 309:R1512-20. [PMID: 26468263 DOI: 10.1152/ajpregu.00380.2015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 10/10/2015] [Indexed: 11/22/2022]
Abstract
Hyperbaric oxygen (HBO) is a major therapeutic treatment for ischemic ulcerations that perforate skin and underlying muscle in diabetic patients. These lesions do not heal effectively, in part, because of the hypoxic microvascular O2 partial pressures (PmvO2 ) resulting from diabetes-induced cardiovascular dysfunction, which alters the dynamic balance between O2 delivery (Q̇o2) and utilization (V̇o2) rates. We tested the hypothesis that HBO in diabetic muscle would exacerbate the hyperoxic PmvO2 dynamics due, in part, to a reduction or slowing of the cardiovascular, sympathetic nervous, and respiratory system responses to acute HBO exposure. Adult male Wistar rats were divided randomly into diabetic (DIA: streptozotocin ip) and healthy (control) groups. A small animal hyperbaric chamber was pressurized with oxygen (100% O2) to 3.0 atmospheres absolute (ATA) at 0.2 ATA/min. Phosphorescence quenching techniques were used to measure PmvO2 in tibialis anterior muscle of anesthetized rats during HBO. Lumbar sympathetic nerve activity (LSNA), heart rate (HR), and respiratory rate (RR) were measured electrophysiologically. During the normobaric hyperoxia and HBO, DIA tibialis anterior PmvO2 increased faster (mean response time, CONT 78 ± 8, DIA 55 ± 8 s, P < 0.05) than CONT. Subsequently, PmvO2 remained elevated at similar levels in CONT and DIA muscles until normobaric normoxic recovery where the DIA PmvO2 retained its hyperoxic level longer than CONT. Sympathetic nervous system and cardiac and respiratory responses to HBO were slower in DIA vs. CONT. Specifically the mean response times for RR (CONT: 6 ± 1 s, DIA: 29 ± 4 s, P < 0.05), HR (CONT: 16 ± 1 s, DIA: 45 ± 5 s, P < 0.05), and LSNA (CONT: 140 ± 16 s, DIA: 247 ± 34 s, P < 0.05) were greater following HBO onset in DIA than CONT. HBO treatment increases tibialis anterior muscle PmvO2 more rapidly and for a longer duration in DIA than CONT, but not to a greater level. Whereas respiratory, cardiovascular, and LSNA responses to HBO are profoundly slowed in DIA, only the cardiovascular arm (via HR) may contribute to the muscle vascular incompetence and these faster PmvO2 kinetics.
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Affiliation(s)
- Kohei Yamakoshi
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Tokyo, Japan
| | - Kazuyoshi Yagishita
- Clinical Center for Sports Medicine and Sports Dentistry, Hyperbaric Medical Center/Sports Medicine Clinical Center, Medical Hospital of Tokyo Medical and Dental University, Tokyo, Japan
| | - Hirotsugu Tsuchimochi
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan; and
| | - Tadakatsu Inagaki
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan; and
| | - Mikiyasu Shirai
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan; and
| | - David C Poole
- Departments of Anatomy & Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Yutaka Kano
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Tokyo, Japan;
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Olver TD, Laughlin MH. Endurance, interval sprint, and resistance exercise training: impact on microvascular dysfunction in type 2 diabetes. Am J Physiol Heart Circ Physiol 2015; 310:H337-50. [PMID: 26408541 DOI: 10.1152/ajpheart.00440.2015] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 09/16/2015] [Indexed: 01/02/2023]
Abstract
Type 2 diabetes (T2D) alters capillary hemodynamics, causes capillary rarefaction in skeletal muscle, and alters endothelial and vascular smooth muscle cell phenotype, resulting in impaired vasodilatory responses. These changes contribute to altered blood flow responses to physiological stimuli, such as exercise and insulin secretion. T2D-induced microvascular dysfunction impairs glucose and insulin delivery to skeletal muscle (and other tissues such as skin and nervous), thereby reducing glucose uptake and perpetuating hyperglycemia and hyperinsulinemia. In patients with T2D, exercise training (EX) improves microvascular vasodilator and insulin signaling and attenuates capillary rarefaction in skeletal muscle. EX-induced changes subsequently augment glucose and insulin delivery as well as glucose uptake. If these adaptions occur in a sufficient amount of tissue, and skeletal muscle in particular, chronic exposure to hyperglycemia and hyperinsulinemia and the risk of microvascular complications in all vascular beds will decrease. We postulate that EX programs that engage as much skeletal muscle mass as possible and recruit as many muscle fibers within each muscle as possible will generate the greatest improvements in microvascular function, providing that the duration of the stimulus is sufficient. Primary improvements in microvascular function occur in tissues (skeletal muscle primarily) engaged during exercise, and secondary improvements in microvascular function throughout the body may result from improved blood glucose control. We propose that the added benefit of combined resistance and aerobic EX programs and of vigorous intensity EX programs is not simply "more is better." Rather, we believe the additional benefit is the result of EX-induced adaptations in and around more muscle fibers, resulting in more muscle mass and the associated microvasculature being changed. Thus, to acquire primary and secondary improvements in microvascular function and improved blood glucose control, EX programs should involve upper and lower body exercise and modulate intensity to augment skeletal muscle fiber recruitment. Under conditions of limited mobility, it may be necessary to train skeletal muscle groups separately to maximize whole body skeletal muscle fiber recruitment.
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Affiliation(s)
- T Dylan Olver
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri;
| | - M Harold Laughlin
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri; Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri
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Poitras VJ, Bentley RF, Hopkins-Rosseel DH, LaHaye SA, Tschakovsky ME. Lack of independent effect of type 2 diabetes beyond characteristic comorbidities and medications on small muscle mass exercising muscle blood flow and exercise tolerance. Physiol Rep 2015; 3:3/8/e12487. [PMID: 26265750 PMCID: PMC4562573 DOI: 10.14814/phy2.12487] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Persons with type 2 diabetes (T2D) are believed to have reduced exercise tolerance; this may be partly due to impaired exercising muscle blood flow (MBF). Whether there is an impact of T2D on exercising MBF within the typical constellation of comorbidities (hypertension, dyslipidemia, obesity) and their associated medications has not been investigated. We tested the hypothesis that small muscle mass exercise tolerance is reduced in persons with T2D versus Controls (matched for age, body mass index, fitness, comorbidities, non-T2D medications) and that this is related to blunted MBF. Eight persons with T2D and eight controls completed a forearm critical force (fCFimpulse) test as a measure of exercise tolerance (10-min intermittent maximal effort forearm contractions; the average contraction impulse in the last 30 sec quantified fCFimpulse). Forearm blood flow (FBF; ultrasound) and mean arterial pressure (MAP; finger photoplethysmography) were measured; forearm vascular conductance (FVK) was calculated. Data are means ± SD, T2D versus Control. fCFimpulse was not different between groups (136.9 ± 47.3 N·sec vs. 163.1 ± 49.7 N·sec, P = 0.371) nor was the ΔFBF from rest to during exercise at fCFimpulse (502.9 ± 144.6 vs. 709.1 ± 289.2 mL/min, P = 0.092), or its determinants ΔFVK and ΔMAP (both P > 0.05), although there was considerable interindividual variability. ΔFBF was strongly related to fCFimpulse (r = 0.727, P = 0.002), providing support for the relationship between oxygen delivery and exercise tolerance. We conclude that small muscle mass exercising MBF and exercise tolerance are not impaired in representative persons with T2D versus appropriately matched controls. This suggests that peripheral vascular control impairment does not contribute to reduced exercise tolerance in this population.
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Affiliation(s)
- Veronica J Poitras
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
| | - Robert F Bentley
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
| | - Diana H Hopkins-Rosseel
- Cardiac Rehabilitation Centre, Hotel Dieu Hospital, Kingston, Ontario, Canada School of Rehabilitation Therapy, Queen's University, Kingston, Ontario, Canada
| | - Stephen A LaHaye
- Cardiac Rehabilitation Centre, Hotel Dieu Hospital, Kingston, Ontario, Canada
| | - Michael E Tschakovsky
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
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Eshima H, Poole DC, Kano Y. In vivo Ca2+ buffering capacity and microvascular oxygen pressures following muscle contractions in diabetic rat skeletal muscles: fiber-type specific effects. Am J Physiol Regul Integr Comp Physiol 2015; 309:R128-37. [DOI: 10.1152/ajpregu.00044.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 05/01/2015] [Indexed: 11/22/2022]
Abstract
In Type 1 diabetes, skeletal muscle resting intracellular Ca2+ concentration ([Ca2+]i) homeostasis is impaired following muscle contractions. It is unclear to what degree this behavior is contingent upon fiber type and muscle oxygenation conditions. We tested the hypotheses that: 1) the rise in resting [Ca2+]i evident in diabetic rat slow-twitch (type I) muscle would be exacerbated in fast-twitch (type II) muscle following contraction; and 2) these elevated [Ca2+]i levels would relate to derangement of microvascular partial pressure of oxygen (PmvO2) rather than sarcoplasmic reticulum dysfunction per se. Adult male Wistar rats were divided randomly into diabetic (DIA: streptozotocin ip) and healthy (CONT) groups. Four weeks later extensor digitorum longus (EDL, predominately type II fibers) and soleus (SOL, predominately type I fibers) muscle contractions were elicited by continuous electrical stimulation (120 s, 100 Hz). Ca2+ imaging was achieved using fura 2-AM in vivo (i.e., circulation intact). DIA increased fatigability in EDL ( P < 0.05) but not SOL. In recovery, SOL [Ca2+]i either returned to its resting baseline within 150 s (CONT 1.00 ± 0.02 at 600 s) or was not elevated in recovery at all (DIA 1.03 ± 0.02 at 600 s, P > 0.05). In recovery, EDL CONT [Ca2+]i also decreased to values not different from baseline (1.06 ± 0.01, P > 0.05) at 600 s. In marked contrast, EDL DIA [Ca2+]i remained elevated for the entire recovery period (i.e., 1.23 ± 0.03 at 600 s, P < 0.05). The inability of [Ca2+]i to return to baseline in EDL DIA was not associated with any reduction of SR Ca2+-ATPase (SERCA) 1 or SERCA2 protein levels (both increased 30–40%, P < 0.05). However, PmvO2 recovery kinetics were markedly slowed in EDL such that mean PmvO2 was substantially depressed (CONT 27.9 ± 2.0 vs. DIA 18.4 ± 2.0 Torr, P < 0.05), and this behavior was associated with the elevated [Ca2+]i. In contrast, this was not the case for SOL ( P > 0.05) in that neither [Ca2+]i nor PmvO2 were deranged in recovery with DIA. In conclusion, recovery of [Ca2+]i homeostasis is impaired in diabetic rat fast-twitch but not slow-twitch muscle in concert with reduced PmvO2 pressures.
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Affiliation(s)
- Hiroaki Eshima
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Tokyo, Japan; and
| | - David C. Poole
- Departments of Anatomy & Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Yutaka Kano
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Tokyo, Japan; and
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Butcher JT, Stanley SC, Brooks SD, Chantler PD, Wu F, Frisbee JC. Impact of increased intramuscular perfusion heterogeneity on skeletal muscle microvascular hematocrit in the metabolic syndrome. Microcirculation 2015; 21:677-87. [PMID: 24828956 DOI: 10.1111/micc.12146] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Accepted: 05/08/2014] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To determine HMV and PS in skeletal muscle of OZR and evaluate the impact of increased microvascular perfusion heterogeneity on mass transport/exchange. METHODS The in situ gastrocnemius muscle from OZR and LZR was examined under control conditions and following pretreatment with TEMPOL (antioxidant)/SQ-29548 (PGH2 /TxA2 receptor antagonist), phentolamine (adrenergic antagonist), or all agents combined. A spike input of a labeled blood tracer cocktail was injected into the perfusing artery. Tracer washout was analyzed using models for HMV and PS. HT was determined in in situ cremaster muscle of OZR and LZR using videomicroscopy. RESULTS HMV was decreased in OZR versus LZR. While TEMPOL/SQ-29548 or phentolamine had minor effects, treatment with all three agents improved HMV in OZR. HT was not different between strains, although variability was increased in OZR, and normalized following treatment with all three agents. PS was reduced in OZR and was not impacted by intervention. CONCLUSIONS Increased microvascular perfusion heterogeneity in OZR reduces HMV in muscle vascular networks and increases its variability, potentially contributing to premature muscle fatigue. While targeted interventions can ameliorate this, the reduced microvascular surface area is not acutely reversible.
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Affiliation(s)
- Joshua T Butcher
- Center for Cardiovascular and Respiratory Sciences, West Virginia University Health Sciences Center, Morgantown, West Virginia, USA; Department of Physiology and Pharmacology, West Virginia University Health Sciences Center, Morgantown, West Virginia, USA
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Poitras VJ, Bentley RF, Hopkins-Rosseel DH, LaHaye SA, Tschakovsky ME. Independent effect of type 2 diabetes beyond characteristic comorbidities and medications on immediate but not continued knee extensor exercise hyperemia. J Appl Physiol (1985) 2015; 119:202-12. [PMID: 26048976 DOI: 10.1152/japplphysiol.00758.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 06/01/2015] [Indexed: 01/23/2023] Open
Abstract
We tested the hypothesis that type 2 diabetes (T2D), when present in the characteristic constellation of comorbidities (obesity, hypertension, dyslipidemia) and medications, slows the dynamic adjustment of exercising muscle perfusion and blunts the steady state relative to that of controls matched for age, body mass index, fitness, comorbidities, and non-T2D medications. Thirteen persons with T2D and 11 who served as controls performed rhythmic single-leg isometric quadriceps exercise (rest-to-6 kg and 6-to-12 kg transitions, 5 min at each intensity). Measurements included leg blood flow (LBF, femoral artery ultrasound), mean arterial pressure (MAP, finger photoplethysmography), and leg vascular conductance (LVK, calculated). Dynamics were quantified using mean response time (MRT). Measures of amplitude were also used to compare response adjustment: the change from baseline to 1) the peak initial response (greatest 1-s average in the first 10 s; ΔLBFPIR, ΔLVKPIR) and 2) the on-transient (average from curve fit at 15, 45, and 75 s; ΔLBFON, ΔLVKON). ΔLBFPIR was significantly blunted in T2D vs. control individuals (P = 0.037); this was due to a tendency for reduced ΔLVKPIR (P = 0.063). In contrast, the overall response speed was not different between groups (MRT P = 0.856, ΔLBFON P = 0.150) nor was the change from baseline to steady state (P = 0.204). ΔLBFPIR, ΔLBFON, and LBF MRT did not differ between rest-to-6 kg and 6-to-12 kg workload transitions (all P > 0.05). Despite a transient amplitude impairment at the onset of exercise, there is no robust or consistent effect of T2D on top of the comorbidities and medications typical of this population on the overall dynamic adjustment of LBF, or the steady-state levels achieved during low- or moderate-intensity exercise.
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Affiliation(s)
- Veronica J Poitras
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
| | - Robert F Bentley
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
| | - Diana H Hopkins-Rosseel
- Cardiac Rehabilitation Centre, Hotel Dieu Hospital, Kingston, Ontario, Canada; and School of Rehabilitation Therapy, Queen's University, Kingston, Ontario, Canada
| | - Stephen A LaHaye
- Cardiac Rehabilitation Centre, Hotel Dieu Hospital, Kingston, Ontario, Canada; and
| | - Michael E Tschakovsky
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada;
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Holdsworth CT, Copp SW, Ferguson SK, Sims GE, Poole DC, Musch TI. Acute inhibition of ATP-sensitive K+ channels impairs skeletal muscle vascular control in rats during treadmill exercise. Am J Physiol Heart Circ Physiol 2015; 308:H1434-42. [PMID: 25820394 DOI: 10.1152/ajpheart.00772.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 03/25/2015] [Indexed: 10/23/2022]
Abstract
The ATP-sensitive K(+) (KATP) channel is part of a class of inward rectifier K(+) channels that can link local O2 availability to vasomotor tone across exercise-induced metabolic transients. The present investigation tested the hypothesis that if KATP channels are crucial to exercise hyperemia, then inhibition via glibenclamide (GLI) would lower hindlimb skeletal muscle blood flow (BF) and vascular conductance during treadmill exercise. In 27 adult male Sprague-Dawley rats, mean arterial pressure, blood lactate concentration, and hindlimb muscle BF (radiolabeled microspheres) were determined at rest (n = 6) and during exercise (n = 6-8, 20, 40, and 60 m/min, 5% incline, i.e., ~60-100% maximal O2 uptake) under control and GLI conditions (5 mg/kg intra-arterial). At rest and during exercise, mean arterial pressure was higher (rest: 17 ± 3%, 20 m/min: 5 ± 1%, 40 m/min: 5 ± 2%, and 60 m/min: 5 ± 1%, P < 0.05) with GLI. Hindlimb muscle BF (20 m/min: 16 ± 7%, 40 m/min: 30 ± 9%, and 60 m/min: 20 ± 8%) and vascular conductance (20 m/min: 20 ± 7%, 40 m/min: 33 ± 8%, and 60 m/min: 24 ± 8%) were lower with GLI during exercise at 20, 40, and 60 m/min, respectively (P < 0.05 for all) but not at rest. Within locomotory muscles, there was a greater fractional reduction present in muscles comprised predominantly of type I and type IIa fibers at all exercise speeds (P < 0.05). Additionally, blood lactate concentration was 106 ± 29% and 44 ± 15% higher during exercise with GLI at 20 and 40 m/min, respectively (P < 0.05). That KATP channel inhibition reduces hindlimb muscle BF during exercise in rats supports the obligatory contribution of KATP channels in large muscle mass exercise-induced hyperemia.
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Affiliation(s)
- Clark T Holdsworth
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; and
| | - Steven W Copp
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; and
| | - Scott K Ferguson
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; and
| | - Gabrielle E Sims
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - David C Poole
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; and Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Timothy I Musch
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; and Department of Kinesiology, Kansas State University, Manhattan, Kansas
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O'Connor E, Green S, Kiely C, O'Shea D, Egaña M. Differential effects of age and type 2 diabetes on dynamic vs. peak response of pulmonary oxygen uptake during exercise. J Appl Physiol (1985) 2015; 118:1031-9. [PMID: 25701005 DOI: 10.1152/japplphysiol.01040.2014] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 02/18/2015] [Indexed: 11/22/2022] Open
Abstract
We investigated if the magnitude of the type 2 diabetes (T2D)-induced impairments in peak oxygen uptake (V̇o2) and V̇o2 kinetics was affected by age. Thirty-three men with T2D (15 middle-aged, 18 older), and 21 nondiabetic (ND) men (11 middle-aged, 10 older) matched by age were recruited. Participants completed four 6-min bouts of constant-load cycling at 80% ventilatory threshold for the determination of V̇o2 kinetics. Cardiac output (inert-gas rebreathing) was recorded at rest and 30 and 240 s during two additional bouts. Peak V̇o2 (determined from a separate graded test) was significantly (P < 0.05) reduced in middle-aged and older men with T2D compared with their respective ND counterparts (middle-aged, 3.2 ± 0.5 vs. 2.5 ± 0.5 l/min; older, 2.7 ± 0.4 vs. 2.4 ± 0.4 l/min), and the magnitude of these impairments was not affected by age. However, the time constant of phase II of the V̇o2 response was only slowed (P < 0.05) in middle-aged men with T2D compared with healthy counterparts, whereas it was similar among older men with and without T2D (middle-aged, 26.8 ± 9.3 vs. 41.6 ± 12.1 s; older, 40.5 ± 7.8 vs. 41.1 ± 8.5 s). Similarly, the "gains" in systemic vascular conductance (estimated from the slope between cardiac output and mean arterial pressure responses) were lower (P < 0.05) in middle-aged men with T2D than ND controls, but similar between the older groups. The results suggest that the mechanisms by which T2D induces significant reductions in peak exercise performance are linked to a slower dynamic response of V̇o2 and reduced systemic vascular conductance responses in middle-aged men, whereas this is not the case in older men.
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Affiliation(s)
- Eamonn O'Connor
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Simon Green
- School of Science and Health and School of Medicine, University of Western Sydney, Sydney, New South Wales, Australia
| | - Catherine Kiely
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Donal O'Shea
- Endocrinology, St. Columcille's and St. Vincent's Hospitals, Dublin, Ireland; and
| | - Mikel Egaña
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland;
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Koga S, Rossiter HB, Heinonen I, Musch TI, Poole DC. Dynamic heterogeneity of exercising muscle blood flow and O2 utilization. Med Sci Sports Exerc 2014; 46:860-76. [PMID: 24091989 DOI: 10.1249/mss.0000000000000178] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Resolving the bases for different physiological functioning or exercise performance within a population is dependent on our understanding of control mechanisms. For example, when most young healthy individuals run or cycle at moderate intensities, oxygen uptake (VO2) kinetics are rapid and the amplitude of the VO2 response is not constrained by O2 delivery. For this to occur, muscle O2 delivery (i.e., blood flow × arterial O2 concentration) must be coordinated superbly with muscle O2 requirements (VO2), the efficacy of which may differ among muscles and distinct fiber types. When the O2 transport system succumbs to the predations of aging or disease (emphysema, heart failure, and type 2 diabetes), muscle O2 delivery and O2 delivery-VO2 matching and, therefore, muscle contractile function become impaired. This forces greater influence of the upstream O2 transport pathway on muscle aerobic energy production, and the O2 delivery-VO2 relationship(s) assumes increased importance. This review is the first of its kind to bring a broad range of available techniques, mostly state of the art, including computer modeling, radiolabeled microspheres, positron emission tomography, magnetic resonance imaging, near-infrared spectroscopy, and phosphorescence quenching to resolve the O2 delivery-VO2 relationships and inherent heterogeneities at the whole body, interorgan, muscular, intramuscular, and microvascular/myocyte levels. Emphasis is placed on the following: 1) intact humans and animals as these provide the platform essential for framing and interpreting subsequent investigations, 2) contemporary findings using novel technological approaches to elucidate O2 delivery-VO2 heterogeneities in humans, and 3) future directions for investigating how normal physiological responses can be explained by O2 delivery-VO2 heterogeneities and the impact of aging/disease on these processes.
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Affiliation(s)
- Shunsaku Koga
- 1Applied Physiology Laboratory, Kobe Design University, JAPAN; 2Division of Respiratory and Critical Care Physiology and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, and School of Biomedical Sciences, University of Leeds, Leeds, UNITED KINGDOM; 3Turku PET Centre and Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku and Turku University Hospital, Turku, FINLAND; Division of Experimental Cardiology, Thoraxcenter, Erasmus MC, University Medical Center Rotterdam, Rotterdam, THE NETHERLANDS; and 4Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS
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Kiely C, O'Connor E, O'Shea D, Green S, Egaña M. Hemodynamic responses during graded and constant-load plantar flexion exercise in middle-aged men and women with type 2 diabetes. J Appl Physiol (1985) 2014; 117:755-64. [DOI: 10.1152/japplphysiol.00555.2014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We tested the hypotheses that type 2 diabetes (T2D) impairs the 1) leg hemodynamic responses to an incremental intermittent plantar-flexion exercise and 2) dynamic responses of leg vascular conductance (LVC) during low-intensity (30% maximal voluntary contraction, MVC) and high-intensity (70% MVC) constant-load plantar-flexion exercise in the supine posture. Forty-four middle-aged individuals with T2D (14 women), and 35 healthy nondiabetic (ND) individuals (18 women) were tested. Leg blood flow (LBF) was measured between each contraction using venous occlusion plethysmography. During the incremental test peak force (Fpeak) relative to MVC was significantly reduced ( P < 0.05) in men and women with T2D compared with their respective nondiabetic counterparts. Peak LBF and the slope of LBF relative to percentage Fpeak were also reduced ( P < 0.05) in women with T2D compared with healthy women (peak blood flow, 460.6 ± 126.8 vs. 628.3 ± 347.7 ml/min; slope, 3.78 ± 1.74 vs. 5.85 ± 3.14 ml·min−1·%Fpeak−1) and in men with T2D compared with nondiabetic men (peak blood flow, 621.7 ± 241.3 vs. 721.2 ± 359.7 ml/min; slope, 5.75 ± 2.66 vs. 6.33 ± 3.63 ml·min−1·%Fpeak−1). During constant-load contractions at 30% MVC T2D did not affect the dynamic responses of LVC (LBF/MAP). However, at 70% MVC [completed by a subgroup of participants (20 with T2D, 6 women; 13 ND, 6 women)] the time constant of the second growth phase of LVC was longer and the amplitude of the first growth phase was lower ( P < 0.05 for both) in men and women with T2D. The results suggest that the T2D-induced impairments in performance of the leg muscles are related to reductions in blood flow in both men and women.
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Affiliation(s)
- Catherine Kiely
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Eamonn O'Connor
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Donal O'Shea
- Endocrinology, St Columcille's and St Vincent's Hospitals, Dublin, Ireland; and
| | - Simon Green
- School of Science and Health and School of Medicine, University of Western Sydney, Sydney, Australia
| | - Mikel Egaña
- Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
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In vivo calcium regulation in diabetic skeletal muscle. Cell Calcium 2014; 56:381-9. [PMID: 25224503 DOI: 10.1016/j.ceca.2014.08.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2014] [Revised: 07/23/2014] [Accepted: 08/09/2014] [Indexed: 01/30/2023]
Abstract
In skeletal muscle, dysfunctional contractile activity has been linked to impaired intracellular Ca(2+) concentration ([Ca(2+)]i) regulation. Muscle force production is impaired and fatigability and muscle fragility deteriorate with diabetes. Use of a novel in vivo model permits investigation of [Ca(2+)]i homeostasis in diabetic skeletal muscle. Within this in vivo environment we have shown that diabetes perturbs the Ca(2+) regulatory system such that resting [Ca(2+)]i homeostasis following muscle contractions is compromised and elevations of [Ca(2+)]i are exacerbated. This review considers the impact of diabetes on the capacity of skeletal muscle to regulate [Ca(2+)]i, following muscle contractions and, in particular, the relationship between muscle fatigue and elevated [Ca(2+)]i in a highly ecologically relevant circulation-intact environment. Importantly, the role of mitochondria in calcium sequestration and the possibility that diabetes impacts this process is explored. Given the profound microcirculatory dysfunction in diabetes this preparation offers the unique opportunity to study the interrelationships among microvascular function, blood-myocyte oxygen flux and [Ca(2+)]i as they relate to enhanced muscle fatigability and exercise intolerance.
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