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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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Halvorson BD, Bao Y, Singh KK, Frisbee SJ, Hachinski V, Whitehead SN, Melling CWJ, Chantler PD, Goldman D, Frisbee JC. Thromboxane-induced cerebral microvascular rarefaction predicts depressive symptom emergence in metabolic disease. J Appl Physiol (1985) 2024; 136:122-140. [PMID: 37969083 DOI: 10.1152/japplphysiol.00410.2023] [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: 06/23/2023] [Revised: 11/14/2023] [Accepted: 11/14/2023] [Indexed: 11/17/2023] Open
Abstract
Previous studies have suggested that the loss of microvessel density in the peripheral circulation with evolving metabolic disease severity represents a significant contributor to impaired skeletal muscle oxygenation and fatigue-resistance. Based on this and our recent work, we hypothesized that cerebral microvascular rarefaction was initiated from the increased prooxidant and proinflammatory environment with metabolic disease and is predictive of the severity of the emergence of depressive symptoms in obese Zucker rats (OZRs). In male OZR, cerebrovascular rarefaction followed the emergence of elevated oxidant and inflammatory environments characterized by increased vascular production of thromboxane A2 (TxA2). The subsequent emergence of depressive symptoms in OZR was associated with the timing and severity of the rarefaction. Chronic intervention with antioxidant (TEMPOL) or anti-inflammation (pentoxifylline) therapy blunted the severity of rarefaction and depressive symptoms, although the effectiveness was limited. Blockade of TxA2 production (dazmegrel) or action (SQ-29548) resulted in a stronger therapeutic effect, suggesting that vascular production and action represent a significant contributor to rarefaction and the emergence of depressive symptoms with chronic metabolic disease (although other pathways clearly contribute as well). A de novo biosimulation of cerebrovascular oxygenation in the face of progressive rarefaction demonstrates the increased probability of generating hypoxic regions within the microvascular networks, which could contribute to impaired neuronal metabolism and the emergence of depressive symptoms. The results of the present study also implicate the potential importance of aggressive prodromic intervention in reducing the severity of chronic complications arising from metabolic disease.NEW & NOTEWORTHY With clinical studies linking vascular disease risk to depressive symptom emergence, we used obese Zucker rats, a model of chronic metabolic disease, to identify potential mechanistic links between these two negative outcomes. Depressive symptom severity correlated with the extent of cerebrovascular rarefaction, after increased vascular oxidant stress/inflammation and TxA2 production. Anti-TxA2 interventions prevasculopathy blunted rarefaction and depressive symptoms, while biosimulation indicated that cerebrovascular rarefaction increased hypoxia within capillary networks as a potential contributing mechanism.
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Affiliation(s)
- Brayden D Halvorson
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Yuki Bao
- Department of Biomedical Engineering, University of Western Ontario, London, Ontario, Canada
| | - Krishna K Singh
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Stephanie J Frisbee
- Department of Pathology and Laboratory Medicine, University of Western Ontario, London, Ontario, Canada
| | - Vladimir Hachinski
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
| | - Shawn N Whitehead
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
| | - C W James Melling
- Department of Kinesiology, University of Western Ontario, London, Ontario, Canada
| | - Paul D Chantler
- Division of Exercise Physiology, West Virginia University, Morgantown, West Virginia, United States
| | - Daniel Goldman
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Jefferson C Frisbee
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
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3
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Menon NJ, Halvorson BD, Alimorad GH, Frisbee JC, Lizotte DJ, Ward AD, Goldman D, Chantler PD, Frisbee SJ. A novel vascular health index: Using data analytics and population health to facilitate mechanistic modeling of microvascular status. Front Physiol 2022; 13:1071813. [PMID: 36561210 PMCID: PMC9763931 DOI: 10.3389/fphys.2022.1071813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 11/25/2022] [Indexed: 12/12/2022] Open
Abstract
The study of vascular function across conditions has been an intensive area of investigation for many years. While these efforts have revealed many factors contributing to vascular health, challenges remain for integrating results across research groups, animal models, and experimental conditions to understand integrated vascular function. As such, the insights attained in clinical/population research from linking datasets, have not been fully realized in the basic sciences, thus frustrating advanced analytics and complex modeling. To achieve comparable advances, we must address the conceptual challenge of defining/measuring integrated vascular function and the technical challenge of combining data across conditions, models, and groups. Here, we describe an approach to establish and validate a composite metric of vascular function by comparing parameters of vascular function in metabolic disease (the obese Zucker rat) to the same parameters in age-matched, "healthy" conditions, resulting in a common outcome measure which we term the vascular health index (VHI). VHI allows for the integration of datasets, thus expanding sample size and permitting advanced modeling to gain insight into the development of peripheral and cerebral vascular dysfunction. Markers of vascular reactivity, vascular wall mechanics, and microvascular network density are integrated in the VHI. We provide a detailed presentation of the development of the VHI and provide multiple measures to assess face, content, criterion, and discriminant validity of the metric. Our results demonstrate how the VHI captures multiple indices of dysfunction in the skeletal muscle and cerebral vasculature with metabolic disease and provide context for an integrated understanding of vascular health under challenged conditions.
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Affiliation(s)
- Nithin J. Menon
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
| | - Brayden D. Halvorson
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
| | - Gabrielle H. Alimorad
- Department of Epidemiology and Biostatistics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
| | - Jefferson C. Frisbee
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
| | - Daniel J. Lizotte
- Department of Epidemiology and Biostatistics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada,Department of Computer Science, Faculty of Science, University of Western Ontario, London, ON, Canada,Lawson Health Research Institute, London, ON, Canada
| | - Aaron D. Ward
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada,Lawson Health Research Institute, London, ON, Canada
| | - Daniel Goldman
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
| | - Paul D. Chantler
- Department of Human Performance-Exercise Physiology, School of Medicine, West Virginia University, Morgantown, WV, United States
| | - Stephanie J. Frisbee
- Department of Epidemiology and Biostatistics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada,Lawson Health Research Institute, London, ON, Canada,Department of Pathology and Laboratory Medicine, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada,*Correspondence: Stephanie J. Frisbee,
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4
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Scalzo RL, Schauer IE, Rafferty D, Knaub LA, Kvaratskhelia N, Johnson TK, Pott GB, Abushamat LA, Whipple MO, Huebschmann AG, Cree-Green M, Reusch JEB, Regensteiner JG. Single-leg exercise training augments in vivo skeletal muscle oxidative flux and vascular content and function in adults with type 2 diabetes. J Physiol 2022; 600:963-978. [PMID: 33569797 PMCID: PMC9006339 DOI: 10.1113/jp280603] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 01/28/2021] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS People with type 2 diabetes (T2D) have impaired skeletal muscle oxidative flux due to limited oxygen delivery. In the current study, this impairment in oxidative flux in people with T2D was abrogated with a single-leg exercise training protocol. Additionally, single-leg exercise training increased skeletal muscle CD31 content, calf blood flow and state 4 mitochondrial respiration in all participants. ABSTRACT Cardiorespiratory fitness is impaired in type 2 diabetes (T2D), conferring significant cardiovascular risk in this population; interventions are needed. Previously, we reported that a T2D-associated decrement in skeletal muscle oxidative flux is ameliorated with acute use of supplemental oxygen, suggesting that skeletal muscle oxygenation is rate-limiting to in vivo mitochondrial oxidative flux during exercise in T2D. We hypothesized that single-leg exercise training (SLET) would improve the T2D-specific impairment in in vivo mitochondrial oxidative flux during exercise. Adults with (n = 19) and without T2D (n = 22) with similar body mass indexes and levels of physical activity participated in two weeks of SLET. Following SLET, in vivo oxidative flux measured by 31 P-MRS increased in participants with T2D, but not people without T2D, measured by the increase in initial phosphocreatine synthesis (P = 0.0455 for the group × exercise interaction) and maximum rate of oxidative ATP synthesis (P = 0.0286 for the interaction). Additionally, oxidative phosphorylation increased in all participants with SLET (P = 0.0209). After SLET, there was no effect of supplemental oxygen on any of the in vivo oxidative flux measurements in either group (P > 0.02), consistent with resolution of the T2D-associated oxygen limitation previously observed at baseline in subjects with T2D. State 4 mitochondrial respiration also improved in muscle fibres ex vivo. Skeletal muscle vasculature content and calf blood flow increased in all participants with SLET (P < 0.0040); oxygen extraction in the calf increased only in T2D (P = 0.0461). SLET resolves the T2D-associated impairment of skeletal muscle in vivo mitochondrial oxidative flux potentially through improved effective blood flow/oxygen delivery.
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Affiliation(s)
- Rebecca L Scalzo
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Division of Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
- Rocky Mountain Regional Veterans Administration Medical Center, Aurora, Colorado, USA
| | - Irene E Schauer
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Rocky Mountain Regional Veterans Administration Medical Center, Aurora, Colorado, USA
| | - Deirdre Rafferty
- Division of General Internal Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Leslie A Knaub
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Rocky Mountain Regional Veterans Administration Medical Center, Aurora, Colorado, USA
| | - Nina Kvaratskhelia
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Taro Kaelix Johnson
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Gregory B Pott
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Rocky Mountain Regional Veterans Administration Medical Center, Aurora, Colorado, USA
| | - Layla A Abushamat
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Rocky Mountain Regional Veterans Administration Medical Center, Aurora, Colorado, USA
| | - Mary O Whipple
- Division of General Internal Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Amy G Huebschmann
- Division of General Internal Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
- Division of Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Melanie Cree-Green
- Division of Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
- Division of Pediatric Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Jane E B Reusch
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Division of General Internal Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
- Division of Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
- Rocky Mountain Regional Veterans Administration Medical Center, Aurora, Colorado, USA
| | - Judith G Regensteiner
- Division of General Internal Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
- Division of Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
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5
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Chilton RJ. Beyond the myocardium: Sodium-glucose co-transporter-2 inhibitors in heart failure. Diabetes Obes Metab 2021; 23:1215-1218. [PMID: 33464709 DOI: 10.1111/dom.14320] [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: 12/04/2020] [Revised: 01/06/2021] [Accepted: 01/14/2021] [Indexed: 11/29/2022]
Affiliation(s)
- Robert J Chilton
- Division of Cardiology, Department of Medicine, University of Texas Health Science Centre at San Antonio, San Antonio, Texas
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6
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Obesity and impaired barrier function after shock: A biomimetic in vitro model using microfluidics. J Trauma Acute Care Surg 2021; 89:544-550. [PMID: 32467464 DOI: 10.1097/ta.0000000000002804] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Impaired microvascular perfusion in the obese patient has been linked to chronic adverse health consequences. The impact on acute illnesses including trauma, sepsis, and hemorrhagic shock (HS) is uncertain. Studies have shown that endothelial glycocalyx and vascular endothelial derangements are causally linked to perfusion abnormalities. Trauma and HS are also associated with impaired microvascular perfusion in which glycocalyx injury and endothelial dysfunction are sentinel events. We postulate that obesity may impact the adverse consequences of HS on the vascular barrier. This was studied in vivo in a biomimetic model of HS using microfluidic technology. METHODS Human umbilical vein endothelial cell monolayers were established in a microfluidic device. Cells were exposed to standard or biomimetic shock conditions (hypoxia plus epinephrine) followed by perfusion from plasma obtained from obese or nonobese subjects. Endothelial glycocalyx and endothelial cellular injury were then determined. RESULTS Plasma from nonobese patients completely reversed glycocalyx and endothelial vascular barrier injury. Plasma from obese patients was only partially protective and was associated with differences in adipokines and other substances in the plasma of these patients. CONCLUSION Our study supports that obesity impairs HS resuscitation. This may be due to microrheological differences between nonobese and obese individuals and may contribute to the poorer outcome in this patient population.
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7
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Roy TK, Secomb TW. Effects of impaired microvascular flow regulation on metabolism-perfusion matching and organ function. Microcirculation 2020; 28:e12673. [PMID: 33236393 DOI: 10.1111/micc.12673] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 11/17/2020] [Indexed: 12/14/2022]
Abstract
Impaired tissue oxygen delivery is a major cause of organ damage and failure in critically ill patients, which can occur even when systemic parameters, including cardiac output and arterial hemoglobin saturation, are close to normal. This review addresses oxygen transport mechanisms at the microcirculatory scale, and how hypoxia may occur in spite of adequate convective oxygen supply. The structure of the microcirculation is intrinsically heterogeneous, with wide variations in vessel diameters and flow pathway lengths, and consequently also in blood flow rates and oxygen levels. The dynamic processes of structural adaptation and flow regulation continually adjust microvessel diameters to compensate for heterogeneity, redistributing flow according to metabolic needs to ensure adequate tissue oxygenation. A key role in flow regulation is played by conducted responses, which are generated and propagated by endothelial cells and signal upstream arterioles to dilate in response to local hypoxia. Several pathophysiological conditions can impair local flow regulation, causing hypoxia and tissue damage leading to organ failure. Therapeutic measures targeted to systemic parameters may not address or may even worsen tissue oxygenation at the microvascular level. Restoration of tissue oxygenation in critically ill patients may depend on restoration of endothelial cell function, including conducted responses.
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Affiliation(s)
- Tuhin K Roy
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Timothy W Secomb
- Department of Physiology, University of Arizona, Tucson, AZ, 85724, USA
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8
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Abushamat LA, McClatchey PM, Scalzo RL, Schauer I, Huebschmann AG, Nadeau KJ, Liu Z, Regensteiner JG, Reusch JEB. Mechanistic Causes of Reduced Cardiorespiratory Fitness in Type 2 Diabetes. J Endocr Soc 2020; 4:bvaa063. [PMID: 32666009 PMCID: PMC7334033 DOI: 10.1210/jendso/bvaa063] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 06/04/2020] [Indexed: 02/06/2023] Open
Abstract
Type 2 diabetes (T2D) has been rising in prevalence in the United States and worldwide over the past few decades and contributes to significant morbidity and premature mortality, primarily due to cardiovascular disease (CVD). Cardiorespiratory fitness (CRF) is a modifiable cardiovascular (CV) risk factor in the general population and in people with T2D. Young people and adults with T2D have reduced CRF when compared with their peers without T2D who are similarly active and of similar body mass index. Furthermore, the impairment in CRF conferred by T2D is greater in women than in men. Various factors may contribute to this abnormality in people with T2D, including insulin resistance and mitochondrial, vascular, and cardiac dysfunction. As proof of concept that understanding the mediators of impaired CRF in T2D can inform intervention, we previously demonstrated that an insulin sensitizer improved CRF in adults with T2D. This review focuses on how contributing factors influence CRF and why they may be compromised in T2D. Functional exercise capacity is a measure of interrelated systems biology; as such, the contribution of derangement in each of these factors to T2D-mediated impairment in CRF is complex and varied. Therefore, successful approaches to improve CRF in T2D should be multifaceted and individually designed. The current status of this research and future directions are outlined.
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Affiliation(s)
- Layla A Abushamat
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | | | - Rebecca L Scalzo
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado.,Rocky Mountain Regional VA, Aurora, Colorado.,Center for Women's Health Research, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Irene Schauer
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado.,Rocky Mountain Regional VA, Aurora, Colorado.,Center for Women's Health Research, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Amy G Huebschmann
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado.,Center for Women's Health Research, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Kristen J Nadeau
- Center for Women's Health Research, University of Colorado, Anschutz Medical Campus, Aurora, Colorado.,Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Zhenqi Liu
- Department of Medicine, University of Virginia, Charlottesville, Virginia
| | - Judith G Regensteiner
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado.,Center for Women's Health Research, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Jane E B Reusch
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado.,Rocky Mountain Regional VA, Aurora, Colorado.,Center for Women's Health Research, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
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9
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Torres Filho IP, Barraza D, Hildreth K, Williams C, Dubick MA. Cremaster muscle perfusion, oxygenation, and heterogeneity revealed by a new automated acquisition system in a rodent model of prolonged hemorrhagic shock. J Appl Physiol (1985) 2019; 127:1548-1561. [PMID: 31670599 DOI: 10.1152/japplphysiol.00570.2019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Local blood flow/oxygen partial pressure (Po2) distributions and flow-Po2 relationships are physiologically relevant. They affect the pathophysiology and treatment of conditions like hemorrhagic shock (HS), but direct noninvasive measures of flow, Po2, and their heterogeneity during prolonged HS are infrequently presented. To fill this void, we report the first quantitative evaluation of flow-Po2 relationships and heterogeneities in normovolemia and during several hours of HS using noninvasive, unbiased, automated acquisition. Anesthetized rats were subjected to tracheostomy, arterial/venous catheterizations, cremaster muscle exteriorization, hemorrhage (40% total blood volume), and laparotomy. Control animals equally instrumented were not subjected to hemorrhage/laparotomy. Every 0.5 h for 4.5 h, noninvasive laser speckle contrast imaging and phosphorescence quenching were employed for nearly 7,000 flow/Po2 measurements in muscles from eight animals, using an automated system. Precise alignment of 16 muscle areas allowed overlapping between flow and oxygenation measurements to evaluate spatial heterogeneity, and repeated measurements were used to estimate temporal heterogeneity. Systemic physiological parameters and blood chemistry were simultaneously assessed by blood samplings replaced with crystalloids. Hemodilution was associated with local hypoxia, but increased flow prevented major oxygen delivery decline. Adding laparotomy and prolonged HS resulted in hypoxia, ischemia, decreased tissue oxygen delivery, and logarithmic flow/Po2 relationships in most regions. Flow and Po2 spatial heterogeneities were higher than their respective temporal heterogeneities, although this did not change significantly over the studied period. This quantitative framework establishes a basis for evaluating therapies aimed at restoring muscle homeostasis, positively impacting outcomes of civilian and military trauma/HS victims.NEW & NOTEWORTHY This is the first study on flow-Po2 relationships during normovolemia, hemodilution, and prolonged hemorrhagic shock using noninvasive methods in multiple skeletal muscle areas of monitored animals. Automated flow/Po2 measurements revealed temporal/spatial heterogeneities, hypoxia, ischemia, and decreased tissue oxygen delivery after trauma/severe hemorrhage. Hemodilution was associated with local hypoxia, but hyperemia prevented a major decline in oxygen delivery. This framework provides a quantitative basis for testing therapeutics that positively impacts muscle homeostasis and outcomes of trauma/hemorrhagic shock victims.
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Affiliation(s)
- Ivo P Torres Filho
- Damage Control Resuscitation, United States Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas
| | - David Barraza
- Damage Control Resuscitation, United States Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas
| | - Kim Hildreth
- Damage Control Resuscitation, United States Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas
| | - Charnae Williams
- Damage Control Resuscitation, United States Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas
| | - Michael A Dubick
- Damage Control Resuscitation, United States Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas
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10
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McClatchey PM, Mignemi NA, Xu Z, Williams IM, Reusch JEB, McGuinness OP, Wasserman DH. Automated quantification of microvascular perfusion. Microcirculation 2018; 25:e12482. [PMID: 29908041 DOI: 10.1111/micc.12482] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 06/11/2018] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Changes in microvascular perfusion have been reported in many diseases, yet the functional significance of altered perfusion is often difficult to determine. This is partly because commonly used techniques for perfusion measurement often rely on either indirect or by-hand approaches. METHODS We developed and validated a fully automated software technique to measure microvascular perfusion in videos acquired by fluorescence microscopy in the mouse gastrocnemius. Acute perfusion responses were recorded following intravenous injections with phenylephrine, SNP, or saline. RESULTS Software-measured capillary flow velocity closely correlated with by-hand measured flow velocity (R2 = 0.91, P < 0.0001). Software estimates of capillary hematocrit also generally agreed with by-hand measurements (R2 = 0.64, P < 0.0001). Detection limits range from 0 to 2000 μm/s, as compared to an average flow velocity of 326 ± 102 μm/s (mean ± SD) at rest. SNP injection transiently increased capillary flow velocity and hematocrit and made capillary perfusion more steady and homogenous. Phenylephrine injection had the opposite effect in all metrics. Saline injection transiently decreased capillary flow velocity and hematocrit without influencing flow distribution or stability. All perfusion metrics were temporally stable without intervention. CONCLUSIONS These results demonstrate a novel and sensitive technique for reproducible, user-independent quantification of microvascular perfusion.
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Affiliation(s)
- Penn Mason McClatchey
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Nicholas A Mignemi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Zhengang Xu
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Ian M Williams
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Jane E B Reusch
- Division of Endocrinology, University of Colorado Medical School, Aurora, Colorado.,Department of Bioengineering, University of Colorado Denver, Denver, Colorado.,Department of Veterans Affairs, Aurora, Colorado
| | - Owen P McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee.,Mouse Metabolic Phenotyping Center, Nashville, Tennessee
| | - David H Wasserman
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee.,Mouse Metabolic Phenotyping Center, Nashville, Tennessee
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11
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Cree-Green M, Scalzo RL, Harrall K, Newcomer BR, Schauer IE, Huebschmann AG, McMillin S, Brown MS, Orlicky D, Knaub L, Nadeau KJ, McClatchey PM, Bauer TA, Regensteiner JG, Reusch JEB. Supplemental Oxygen Improves In Vivo Mitochondrial Oxidative Phosphorylation Flux in Sedentary Obese Adults With Type 2 Diabetes. Diabetes 2018; 67:1369-1379. [PMID: 29643061 PMCID: PMC6463751 DOI: 10.2337/db17-1124] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 03/29/2018] [Indexed: 12/11/2022]
Abstract
Type 2 diabetes is associated with impaired exercise capacity. Alterations in both muscle perfusion and mitochondrial function can contribute to exercise impairment. We hypothesized that impaired muscle mitochondrial function in type 2 diabetes is mediated, in part, by decreased tissue oxygen delivery and would improve with oxygen supplementation. Ex vivo muscle mitochondrial content and respiration assessed from biopsy samples demonstrated expected differences in obese individuals with (n = 18) and without (n = 17) diabetes. Similarly, in vivo mitochondrial oxidative phosphorylation capacity measured in the gastrocnemius muscle via 31P-MRS indicated an impairment in the rate of ADP depletion with rest (27 ± 6 s [diabetes], 21 ± 7 s [control subjects]; P = 0.008) and oxidative phosphorylation (P = 0.046) in type 2 diabetes after isometric calf exercise compared with control subjects. Importantly, the in vivo impairment in oxidative capacity resolved with oxygen supplementation in adults with diabetes (ADP depletion rate 5.0 s faster, P = 0.012; oxidative phosphorylation 0.046 ± 0.079 mmol/L/s faster, P = 0.027). Multiple in vivo mitochondrial measures related to HbA1c These data suggest that oxygen availability is rate limiting for in vivo mitochondrial oxidative exercise recovery measured with 31P-MRS in individuals with uncomplicated diabetes. Targeting muscle oxygenation could improve exercise function in type 2 diabetes.
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Affiliation(s)
- Melanie Cree-Green
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- Division of Pediatric Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Rebecca L Scalzo
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- Division of Endocrinology and Metabolism, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Kylie Harrall
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- School of Pharmacy, University of Colorado Anschutz Medical Campus, Aurora, CO
| | | | - Irene E Schauer
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- Division of Endocrinology and Metabolism, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
- Veterans Affairs Medical Center, Denver, CO
| | - Amy G Huebschmann
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- Division of General Internal Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Shawna McMillin
- Division of General Internal Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Mark S Brown
- Department of Radiology, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - David Orlicky
- Division of Pathology, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Leslie Knaub
- Division of Endocrinology and Metabolism, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Kristen J Nadeau
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- Division of Pediatric Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - P Mason McClatchey
- Division of Endocrinology and Metabolism, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Timothy A Bauer
- Division of General Internal Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Judith G Regensteiner
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- Division of General Internal Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
- Division of Cardiology, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Jane E B Reusch
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- Veterans Affairs Medical Center, Denver, CO
- Division of General Internal Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
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12
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Kharche SR, So A, Salerno F, Lee TY, Ellis C, Goldman D, McIntyre CW. Computational Assessment of Blood Flow Heterogeneity in Peritoneal Dialysis Patients' Cardiac Ventricles. Front Physiol 2018; 9:511. [PMID: 29867555 PMCID: PMC5968396 DOI: 10.3389/fphys.2018.00511] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 04/20/2018] [Indexed: 01/28/2023] Open
Abstract
Dialysis prolongs life but augments cardiovascular mortality. Imaging data suggests that dialysis increases myocardial blood flow (BF) heterogeneity, but its causes remain poorly understood. A biophysical model of human coronary vasculature was used to explain the imaging observations, and highlight causes of coronary BF heterogeneity. Post-dialysis CT images from patients under control, pharmacological stress (adenosine), therapy (cooled dialysate), and adenosine and cooled dialysate conditions were obtained. The data presented disparate phenotypes. To dissect vascular mechanisms, a 3D human vasculature model based on known experimental coronary morphometry and a space filling algorithm was implemented. Steady state simulations were performed to investigate the effects of altered aortic pressure and blood vessel diameters on myocardial BF heterogeneity. Imaging showed that stress and therapy potentially increased mean and total BF, while reducing heterogeneity. BF histograms of one patient showed multi-modality. Using the model, it was found that total coronary BF increased as coronary perfusion pressure was increased. BF heterogeneity was differentially affected by large or small vessel blocking. BF heterogeneity was found to be inversely related to small blood vessel diameters. Simulation of large artery stenosis indicates that BF became heterogeneous (increase relative dispersion) and gave multi-modal histograms. The total transmural BF as well as transmural BF heterogeneity reduced due to large artery stenosis, generating large patches of very low BF regions downstream. Blocking of arteries at various orders showed that blocking larger arteries results in multi-modal BF histograms and large patches of low BF, whereas smaller artery blocking results in augmented relative dispersion and fractal dimension. Transmural heterogeneity was also affected. Finally, the effects of augmented aortic pressure in the presence of blood vessel blocking shows differential effects on BF heterogeneity as well as transmural BF. Improved aortic blood pressure may improve total BF. Stress and therapy may be effective if they dilate small vessels. A potential cause for the observed complex BF distributions (multi-modal BF histograms) may indicate existing large vessel stenosis. The intuitive BF heterogeneity methods used can be readily used in clinical studies. Further development of the model and methods will permit personalized assessment of patient BF status.
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Affiliation(s)
- Sanjay R Kharche
- Kidney Clinical Research Unit, Lawson's Health Research Institute, Victoria Hospital, London, ON, Canada.,Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Aaron So
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.,Robarts Research Institute, University of Western Ontario, London, ON, Canada
| | - Fabio Salerno
- Kidney Clinical Research Unit, Lawson's Health Research Institute, Victoria Hospital, London, ON, Canada
| | - Ting-Yim Lee
- Robarts Research Institute, University of Western Ontario, London, ON, Canada
| | - Chris Ellis
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Daniel Goldman
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Christopher W McIntyre
- Kidney Clinical Research Unit, Lawson's Health Research Institute, Victoria Hospital, London, ON, Canada.,Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
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13
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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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14
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Wahl MP, Scalzo RL, Regensteiner JG, Reusch JEB. Mechanisms of Aerobic Exercise Impairment in Diabetes: A Narrative Review. Front Endocrinol (Lausanne) 2018; 9:181. [PMID: 29720965 PMCID: PMC5915473 DOI: 10.3389/fendo.2018.00181] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 04/04/2018] [Indexed: 12/21/2022] Open
Abstract
The prevalence of diabetes in the United States and globally has been rapidly increasing over the last several decades. There are now estimated to be 30.3 million people in the United States and 422 million people worldwide with diabetes. Diabetes is associated with a greatly increased risk of cardiovascular mortality, which is the leading cause of death in adults with diabetes. While exercise training is a cornerstone of diabetes treatment, people with diabetes have well-described aerobic exercise impairments that may create an additional diabetes-specific barrier to adding regular exercise to their lifestyle. Physiologic mechanisms linked to exercise impairment in diabetes include insulin resistance, cardiac abnormalities, mitochondrial function, and the ability of the body to supply oxygen. In this paper, we highlight the abnormalities of exercise in type 2 diabetes as well as potential therapeutic approaches.
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Affiliation(s)
- Matthew P. Wahl
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, CO, United States
- Veterans Administration Eastern Colorado Health Care System, Denver, CO, United States
| | - Rebecca L. Scalzo
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, CO, United States
- Center for Women’s Health Research, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
| | - Judith G. Regensteiner
- Center for Women’s Health Research, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
- Division of General Internal Medicine, University of Colorado School of Medicine, Aurora, CO, United States
| | - Jane E. B. Reusch
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, CO, United States
- Veterans Administration Eastern Colorado Health Care System, Denver, CO, United States
- Center for Women’s Health Research, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
- *Correspondence: Jane E. B. Reusch,
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15
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Mason McClatchey P, Bauer TA, Regensteiner JG, Schauer IE, Huebschmann AG, Reusch JEB. Dissociation of local and global skeletal muscle oxygen transport metrics in type 2 diabetes. J Diabetes Complications 2017; 31:1311-1317. [PMID: 28571935 PMCID: PMC5891220 DOI: 10.1016/j.jdiacomp.2017.05.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 05/05/2017] [Accepted: 05/08/2017] [Indexed: 01/28/2023]
Abstract
AIMS Exercise capacity is impaired in type 2 diabetes, and this impairment predicts excess morbidity and mortality. This defect appears to involve excess skeletal muscle deoxygenation, but the underlying mechanisms remain unclear. We hypothesized that reduced blood flow, reduced local recruitment of blood volume/hematocrit, or both contribute to excess skeletal muscle deoxygenation in type 2 diabetes. METHODS In patients with (n=23) and without (n=18) type 2 diabetes, we recorded maximal reactive hyperemic leg blood flow, peak oxygen utilization during cycling ergometer exercise (VO2peak), and near-infrared spectroscopy-derived measures of exercise-induced changes in skeletal muscle oxygenation and blood volume/hematocrit. RESULTS We observed a significant increase (p<0.05) in skeletal muscle deoxygenation in type 2 diabetes despite similar blood flow and recruitment of local blood volume/hematocrit. Within the control group skeletal muscle deoxygenation, local recruitment of microvascular blood volume/hematocrit, blood flow, and VO2peak are all mutually correlated. None of these correlations were preserved in type 2 diabetes. CONCLUSIONS These results suggest that in type 2 diabetes 1) skeletal muscle oxygenation is impaired, 2) this impairment may occur independently of bulk blood flow or local recruitment of blood volume/hematocrit, and 3) local and global metrics of oxygen transport are dissociated.
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Affiliation(s)
- P Mason McClatchey
- Division of Endocrinology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States; Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, United States; Department of Medicine, Denver Veterans Affairs Medical Center, Denver, CO, United States
| | - Timothy A Bauer
- Division of General Internal Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Judith G Regensteiner
- Division of General Internal Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States; Center for Women's Health Research, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Irene E Schauer
- Division of Endocrinology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States; Department of Medicine, Denver Veterans Affairs Medical Center, Denver, CO, United States
| | - Amy G Huebschmann
- Division of General Internal Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States; Center for Women's Health Research, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Jane E B Reusch
- Division of Endocrinology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States; Department of Medicine, Denver Veterans Affairs Medical Center, Denver, CO, United States; Center for Women's Health Research, University of Colorado Anschutz Medical Campus, Aurora, CO, United States.
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16
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Dipla K, Triantafyllou A, Koletsos N, Papadopoulos S, Sachpekidis V, Vrabas IS, Gkaliagkousi E, Zafeiridis A, Douma S. Impaired Muscle Oxygenation and Elevated Exercise Blood Pressure in Hypertensive Patients: Links With Vascular Stiffness. Hypertension 2017; 70:444-451. [PMID: 28607132 DOI: 10.1161/hypertensionaha.117.09558] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 04/21/2017] [Accepted: 05/14/2017] [Indexed: 12/31/2022]
Abstract
This study examined in vivo (1) skeletal muscle oxygenation and microvascular function, at rest and during handgrip exercise, and (2) their association with macrovascular function and exercise blood pressure (BP), in newly diagnosed, never-treated patients with hypertension and normotensive individuals. Ninety-one individuals (51 hypertensives and 40 normotensives) underwent office and 24-hour ambulatory BP, arterial stiffness, and central aortic BP assessment, followed by a 5-minute arterial occlusion and a 3-minute submaximal handgrip exercise. Changes in muscle oxygenated and deoxygenated hemoglobin and tissue oxygen saturation were continuously monitored by near-infrared spectroscopy and beat-by-beat BP by Finapres. Hypertensives had higher (P<0.001) central aortic BP and pulse wave velocity versus normotensives and exhibited (1) a blunted tissue oxygen saturation response during occlusion, with slower (P=0.006) deoxygenation rate, suggesting reduced muscle oxidative capacity, and (2) a slower reoxygenation rate and blunted hyperemic response (P<0.05), showing reduced microvascular reactivity. Muscle oxygenation responses were correlated with aortic systolic and pulse pressure and augmentation index (P<0.05; age and body mass index (BMI) adjusted). When exercising at the same submaximal intensity, hypertensives required a significantly greater (P<0.001) increase in BP for achieving similar muscle oxygenation levels as normotensives. This response was correlated with the magnitude of microvascular hyperemia and aortic BP. In conclusion, nontreated patients with hypertension exhibit prominent reductions in in vivo indices of skeletal muscle oxidative capacity, suggestive of mitochondrial dysfunction, and blunted muscle microvascular reactivity. These dysfunctions were associated with higher aortic systolic BP and arterial stiffness. Dysregulations in muscle oxygen delivery/utilization and microvascular stiffness, in hypertensive patients, partially contribute to their exaggerated BP during exercise.
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Affiliation(s)
- Konstantina Dipla
- From the Exercise Physiology and Biochemistry Laboratory, Department of Sports Science at Serres (K.D., S.P., I.S.V., A.Z.) and 3rd Department of Internal Medicine, Papageorgiou Hospital (A.T., N.K., E.G., S.D.), Aristotle University of Thessaloniki, Greece; and 2nd Cardiology Department, Papageorgiou Hospital, Thessaloniki, Greece (V.S.).
| | - Areti Triantafyllou
- From the Exercise Physiology and Biochemistry Laboratory, Department of Sports Science at Serres (K.D., S.P., I.S.V., A.Z.) and 3rd Department of Internal Medicine, Papageorgiou Hospital (A.T., N.K., E.G., S.D.), Aristotle University of Thessaloniki, Greece; and 2nd Cardiology Department, Papageorgiou Hospital, Thessaloniki, Greece (V.S.)
| | - Nikolaos Koletsos
- From the Exercise Physiology and Biochemistry Laboratory, Department of Sports Science at Serres (K.D., S.P., I.S.V., A.Z.) and 3rd Department of Internal Medicine, Papageorgiou Hospital (A.T., N.K., E.G., S.D.), Aristotle University of Thessaloniki, Greece; and 2nd Cardiology Department, Papageorgiou Hospital, Thessaloniki, Greece (V.S.)
| | - Stavros Papadopoulos
- From the Exercise Physiology and Biochemistry Laboratory, Department of Sports Science at Serres (K.D., S.P., I.S.V., A.Z.) and 3rd Department of Internal Medicine, Papageorgiou Hospital (A.T., N.K., E.G., S.D.), Aristotle University of Thessaloniki, Greece; and 2nd Cardiology Department, Papageorgiou Hospital, Thessaloniki, Greece (V.S.)
| | - Vasileios Sachpekidis
- From the Exercise Physiology and Biochemistry Laboratory, Department of Sports Science at Serres (K.D., S.P., I.S.V., A.Z.) and 3rd Department of Internal Medicine, Papageorgiou Hospital (A.T., N.K., E.G., S.D.), Aristotle University of Thessaloniki, Greece; and 2nd Cardiology Department, Papageorgiou Hospital, Thessaloniki, Greece (V.S.)
| | - Ioannis S Vrabas
- From the Exercise Physiology and Biochemistry Laboratory, Department of Sports Science at Serres (K.D., S.P., I.S.V., A.Z.) and 3rd Department of Internal Medicine, Papageorgiou Hospital (A.T., N.K., E.G., S.D.), Aristotle University of Thessaloniki, Greece; and 2nd Cardiology Department, Papageorgiou Hospital, Thessaloniki, Greece (V.S.)
| | - Eugenia Gkaliagkousi
- From the Exercise Physiology and Biochemistry Laboratory, Department of Sports Science at Serres (K.D., S.P., I.S.V., A.Z.) and 3rd Department of Internal Medicine, Papageorgiou Hospital (A.T., N.K., E.G., S.D.), Aristotle University of Thessaloniki, Greece; and 2nd Cardiology Department, Papageorgiou Hospital, Thessaloniki, Greece (V.S.)
| | - Andreas Zafeiridis
- From the Exercise Physiology and Biochemistry Laboratory, Department of Sports Science at Serres (K.D., S.P., I.S.V., A.Z.) and 3rd Department of Internal Medicine, Papageorgiou Hospital (A.T., N.K., E.G., S.D.), Aristotle University of Thessaloniki, Greece; and 2nd Cardiology Department, Papageorgiou Hospital, Thessaloniki, Greece (V.S.)
| | - Stella Douma
- From the Exercise Physiology and Biochemistry Laboratory, Department of Sports Science at Serres (K.D., S.P., I.S.V., A.Z.) and 3rd Department of Internal Medicine, Papageorgiou Hospital (A.T., N.K., E.G., S.D.), Aristotle University of Thessaloniki, Greece; and 2nd Cardiology Department, Papageorgiou Hospital, Thessaloniki, Greece (V.S.)
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