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Belbis MD, Yap Z, Hobart SE, Ferguson SK, Hirai DM. Effects of acute phosphodiesterase type 5 inhibition on skeletal muscle interstitial PO 2 during contractions and recovery. Nitric Oxide 2024; 142:16-25. [PMID: 37979932 DOI: 10.1016/j.niox.2023.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 10/26/2023] [Accepted: 11/14/2023] [Indexed: 11/20/2023]
Abstract
The oxygen partial pressure within the interstitial space (PO2is; mmHg) provides the driving force for oxygen diffusion into the myocyte thereby supporting oxidative phosphorylation. We tested the hypothesis that potentiation of the nitric oxide pathway with sildenafil (phosphodiesterase type 5 inhibitor) would enhance PO2is during muscle metabolic transitions, thereby slowing PO2is on- and accelerating PO2is off-kinetics. The rat spinotrapezius muscle (n = 17) was exposed for PO2is measurements via phosphorescence quenching under control (CON), low-dose sildenafil (1 mg/kg i.a., SIL1) and high-dose sildenafil (7 mg/kg i.a., SIL7). Data were collected at rest and during submaximal twitch contractions (1 Hz, 4-6 V, 3 min) and recovery (3 min). Mean arterial blood pressure (MAP; mmHg) was reduced with both SIL1 (pre:132 ± 5; post:99 ± 5) and SIL7 (pre:111 ± 6; post:99 ± 4) (p < 0.05). SIL7 elevated resting PO2is (18.4 ± 1.1) relative to both CON (15.7 ± 0.7) and SIL1 (15.2 ± 0.7) (p < 0.05). In addition, SIL7 increased end-recovery PO2is (17.7 ± 1.6) compared to CON (12.8 ± 0.9) and SIL1 (13.4 ± 0.8) (p < 0.05). The overall PO2is response during recovery (i.e., area under the PO2is curve) was greater in SIL7 (4107 ± 444) compared to CON (3493 ± 222) and SIL1 (3114 ± 205 mmHg s) (p < 0.05). Contrary to our hypothesis, there was no impact of acute SIL (1 or 7 mg/kg) on the speed of the PO2is response during contractions or recovery (p > 0.05). However, sildenafil lowered MAP and improved skeletal muscle interstitial oxygenation in healthy rats. Specifically, SIL7 enhanced PO2is at rest and during recovery from submaximal muscle contractions. Potentiation of the nitric oxide pathway with sildenafil enhances microvascular blood-myocyte O2 transport and is expected to improve repeated bouts of contractile activity.
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Affiliation(s)
- Michael D Belbis
- Department of Health and Kinesiology, Purdue University, West Lafayette, IN, USA; Department of Exercise Science, Aurora University, Aurora, IL, USA
| | - Zhen Yap
- Department of Health and Kinesiology, Purdue University, West Lafayette, IN, USA
| | - Sara E Hobart
- Department of Health and Kinesiology, Purdue University, West Lafayette, IN, USA
| | - Scott K Ferguson
- Department of Human Factors and Behavioral Neurobiology, Embry-Riddle Aeronautical University, Daytona Beach, FL, USA
| | - Daniel M Hirai
- Department of Health and Kinesiology, Purdue University, West Lafayette, IN, USA.
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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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3
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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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Poole DC, Pittman RN, Musch TI, Østergaard L. August Krogh's theory of muscle microvascular control and oxygen delivery: a paradigm shift based on new data. J Physiol 2020; 598:4473-4507. [PMID: 32918749 DOI: 10.1113/jp279223] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 07/13/2020] [Indexed: 12/16/2022] Open
Abstract
August Krogh twice won the prestigious international Steegen Prize, for nitrogen metabolism (1906) and overturning the concept of active transport of gases across the pulmonary epithelium (1910). Despite this, at the beginning of 1920, the consummate experimentalist was relatively unknown worldwide and even among his own University of Copenhagen faculty. But, in early 1919, he had submitted three papers to Dr Langley, then editor of The Journal of Physiology in England. These papers coalesced anatomical observations of skeletal muscle capillary numbers with O2 diffusion theory to propose a novel active role for capillaries that explained the prodigious increase in blood-muscle O2 flux from rest to exercise. Despite his own appraisal of the first two papers as "rather dull" to his friend, the eminent Cambridge respiratory physiologist, Joseph Barcroft, Krogh believed that the third one, dealing with O2 supply and capillary regulation, was"interesting". These papers, which won Krogh an unopposed Nobel Prize for Physiology or Medicine in 1920, form the foundation for this review. They single-handedly transformed the role of capillaries from passive conduit and exchange vessels, functioning at the mercy of their upstream arterioles, into independent contractile units that were predominantly closed at rest and opened actively during muscle contractions in a process he termed 'capillary recruitment'. Herein we examine Krogh's findings and some of the experimental difficulties he faced. In particular, the boundary conditions selected for his model (e.g. heavily anaesthetized animals, negligible intramyocyte O2 partial pressure, binary open-closed capillary function) have not withstood the test of time. Subsequently, we update the reader with intervening discoveries that underpin our current understanding of muscle microcirculatory control and place a retrospectroscope on Krogh's discoveries. The perspective is presented that the imprimatur of the Nobel Prize, in this instance, may have led scientists to discount compelling evidence. Much as he and Marie Krogh demonstrated that active transport of gases across the blood-gas barrier was unnecessary in the lung, capillaries in skeletal muscle do not open and close spontaneously or actively, nor is this necessary to account for the increase in blood-muscle O2 flux during exercise. Thus, a contemporary model of capillary function features most muscle capillaries supporting blood flow at rest, and, rather than capillaries actively vasodilating from rest to exercise, increased blood-myocyte O2 flux occurs predominantly via elevating red blood cell and plasma flux in already flowing capillaries. Krogh is lauded for his brilliance as an experimentalist and for raising scientific questions that led to fertile avenues of investigation, including the study of microvascular function.
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Affiliation(s)
- David C Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University Manhattan, Manhattan, KS, 66506, USA
| | - Roland N Pittman
- Department of Physiology and Biophysics, Virginia Commonwealth University Richmond, Richmond, VA, 23298-0551, USA
| | - Timothy I Musch
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University Manhattan, Manhattan, KS, 66506, USA
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience, Aarhus University, Denmark
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5
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Didier KD, Hammer SM, Alexander AM, Caldwell JT, Sutterfield SL, Smith JR, Ade CJ, Barstow TJ. Microvascular blood flow during vascular occlusion tests assessed by diffuse correlation spectroscopy. Exp Physiol 2019; 105:201-210. [DOI: 10.1113/ep087866] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 10/29/2019] [Indexed: 01/13/2023]
Affiliation(s)
- Kaylin D. Didier
- Department of Kinesiology Kansas State University Manhattan KS USA
| | - Shane M. Hammer
- Department of Kinesiology Kansas State University Manhattan KS USA
| | | | | | | | - Joshua R. Smith
- Department of Kinesiology Kansas State University Manhattan KS USA
| | - Carl J. Ade
- Department of Kinesiology Kansas State University Manhattan KS USA
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6
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Hirai DM, Craig JC, Colburn TD, Eshima H, Kano Y, Musch TI, Poole DC. Skeletal muscle interstitial Po 2 kinetics during recovery from contractions. J Appl Physiol (1985) 2019; 127:930-939. [PMID: 31369325 DOI: 10.1152/japplphysiol.00297.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The oxygen partial pressure in the interstitial space (Po2 is) drives O2 into the myocyte via diffusion, thus supporting oxidative phosphorylation. Although crucial for metabolic recovery and the capacity to perform repetitive tasks, the time course of skeletal muscle Po2 is during recovery from contractions remains unknown. We tested the hypothesis that Po2 is would recover to resting values and display considerable on-off asymmetry (fast on-, slow off-kinetics), reflective of asymmetric capillary hemodynamics. Microvascular Po2 (Po2 mv) was also evaluated to test the hypothesis that a significant transcapillary gradient (ΔPo2 = Po2 mv - Po2 is) would be sustained during recovery. Po2 mv and Po2 is (expressed in mmHg) were determined via phosphorescence quenching in the exposed rat spinotrapezius muscle during and after submaximal twitch contractions (n = 12). Po2 is rose exponentially (P < 0.05) from end-contraction (11.1 ± 5.1), such that the end-recovery value (17.9 ± 7.9) was not different from resting Po2 is (18.5 ± 8.1; P > 0.05). Po2 is off-kinetics were slower than on-kinetics (mean response time: 53.1 ± 38.3 versus 18.5 ± 7.3 s; P < 0.05). A significant transcapillary ΔPo2 observed at end-contraction (16.6 ± 7.4) was maintained throughout recovery (end-recovery: 18.8 ± 9.6; P > 0.05). Consistent with our hypotheses, muscle Po2 is recovered to resting values with slower off-kinetics compared with the on-transient in line with the on-off asymmetry for capillary hemodynamics. Maintenance of a substantial transcapillary ΔPo2 during recovery supports that the microvascular-interstitium interface provides considerable resistance to O2 transport. As dictated by Fick's law (V̇o2 = Do2 × ΔPo2), modulation of O2 flux (V̇o2) during recovery must be achieved via corresponding changes in effective diffusing capacity (Do2; mainly capillary red blood cell hemodynamics and distribution) in the face of unaltered ΔPo2.NEW & NOTEWORTHY Capillary blood-myocyte O2 flux (V̇o2) is determined by effective diffusing capacity (Do2; mainly erythrocyte hemodynamics and distribution) and microvascular-interstitial Po2 gradients (ΔPo2 = Po2 mv - Po2 is). We show that Po2 is demonstrates on-off asymmetry consistent with Po2 mv and erythrocyte kinetics during metabolic transitions. A substantial transcapillary ΔPo2 was preserved during recovery from contractions, indicative of considerable resistance to O2 diffusion at the microvascular-interstitium interface. This reveals that effective Do2 declines in step with V̇o2 during recovery, as per Fick's law.
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Affiliation(s)
- Daniel M Hirai
- Department of Health and Kinesiology, Purdue University, West Lafayette, Indiana.,Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Jesse C Craig
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas.,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
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Hiroaki Eshima
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Yutaka Kano
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
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7
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Barstow TJ. Understanding near infrared spectroscopy and its application to skeletal muscle research. J Appl Physiol (1985) 2019; 126:1360-1376. [PMID: 30844336 DOI: 10.1152/japplphysiol.00166.2018] [Citation(s) in RCA: 203] [Impact Index Per Article: 40.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Near infrared spectroscopy (NIRS) is a powerful noninvasive tool with which to study the matching of oxygen delivery to oxygen utilization and the number of new publications utilizing this technique has increased exponentially in the last 20 yr. By measuring the state of oxygenation of the primary heme compounds in skeletal muscle (hemoglobin and myoglobin), greater understanding of the underlying control mechanisms that couple perfusive and diffusive oxygen delivery to oxidative metabolism can be gained from the laboratory to the athletic field to the intensive care unit or emergency room. However, the field of NIRS has been complicated by the diversity of instrumentation, the inherent limitations of some of these technologies, the associated diversity of terminology, and a general lack of standardization of protocols. This Cores of Reproducibility in Physiology (CORP) will describe in basic but important detail the most common methodologies of NIRS, their strengths and limitations, and discuss some of the potential confounding factors that can affect the quality and reproducibility of NIRS data. Recommendations are provided to reduce the variability and errors in data collection, analysis, and interpretation. The goal of this CORP is to provide readers with a greater understanding of the methodology, limitations, and best practices so as to improve the reproducibility of NIRS research in skeletal muscle.
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Affiliation(s)
- Thomas J Barstow
- Department of Kinesiology, Kansas State University , Manhattan, Kansas
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8
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Hammer SM, Alexander AM, Didier KD, Smith JR, Caldwell JT, Sutterfield SL, Ade CJ, Barstow TJ. The noninvasive simultaneous measurement of tissue oxygenation and microvascular hemodynamics during incremental handgrip exercise. J Appl Physiol (1985) 2018; 124:604-614. [DOI: 10.1152/japplphysiol.00815.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Limb blood flow increases linearly with exercise intensity; however, invasive measurements of muscle microvascular blood flow during incremental exercise have demonstrated submaximal plateaus. We tested the hypotheses that 1) brachial artery blood flow (Q̇BA) would increase with increasing exercise intensity until task failure, 2) blood flow index of the flexor digitorum superficialis (BFIFDS) measured noninvasively via diffuse correlation spectroscopy would plateau at a submaximal work rate, and 3) muscle oxygenation characteristics (total-[heme], deoxy-[heme], and percentage saturation) measured noninvasively with near-infrared spectroscopy would demonstrate a plateau at a similar work rate as BFIFDS. Sixteen subjects (23.3 ± 3.9 yr, 170.8 ± 1.9 cm, 72.8 ± 3.4 kg) participated in this study. Peak power (Ppeak) was determined for each subject (1.8 ± 0.4 W) via an incremental handgrip exercise test. Q̇BA, BFIFDS, total-[heme], deoxy-[heme], and percentage saturation were measured during each stage of the exercise test. On a subsequent testing day, muscle activation measurements of the FDS (RMSFDS) were collected during each stage of an identical incremental handgrip exercise test via electromyography from a subset of subjects ( n = 7). Q̇BA increased with exercise intensity until the final work rate transition ( P < 0.05). No increases in BFIFDS or muscle oxygenation characteristics were observed at exercise intensities greater than 51.5 ± 22.9% of Ppeak. No submaximal plateau in RMSFDS was observed. Whereas muscle activation of the FDS increased until task failure, noninvasively measured indices of perfusive and diffusive muscle microvascular oxygen delivery demonstrated submaximal plateaus. NEW & NOTEWORTHY Invasive measurements of muscle microvascular blood flow during incremental exercise have demonstrated submaximal plateaus. We demonstrate that indices of perfusive and diffusive microvascular oxygen transport to skeletal muscle, measured completely noninvasively, plateau at submaximal work rates during incremental exercise, even though limb blood flow and muscle recruitment continued to increase.
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Affiliation(s)
- Shane M. Hammer
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | | | - Kaylin D. Didier
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Joshua R. Smith
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Jacob T. Caldwell
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | | | - Carl J. Ade
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Thomas J. Barstow
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
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9
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Drescher U, Mookerjee S, Steegmanns A, Knicker A, Hoffmann U. Gas exchange kinetics following concentric-eccentric isokinetic arm and leg exercise. Respir Physiol Neurobiol 2017; 240:53-60. [PMID: 28215595 DOI: 10.1016/j.resp.2017.02.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/08/2017] [Accepted: 02/09/2017] [Indexed: 10/20/2022]
Abstract
PURPOSE To evaluate the effects of exercise velocity (60, 150, 240deg∙s-1) and muscle mass (arm vs leg) on changes in gas exchange and arterio-venous oxygen content difference (avDO2) following high-intensity concentric-eccentric isokinetic exercise. METHODS Fourteen subjects (26.9±3.1years) performed a 3×20-repetition isokinetic exercise protocol. Recovery beat-to-beat cardiac output (CO) and breath-by-breath gas exchange were recorded to determine post-exercise half-time (t1/2) for oxygen uptake (V˙O2pulm), carbon dioxide output (V˙CO2pulm), and ventilation (V˙E). RESULTS Significant differences of the t1/2 values were identified between 60 and 150deg∙s-1. Significant differences in the t1/2 values were observed between V˙O2pulm and V˙CO2pulm and between V˙CO2pulm and V˙E. The time to attain the first avDO2-peak showed significant differences between arm and leg exercise. CONCLUSIONS The present study illustrates, that V˙O2pulm kinetics are distorted due to non-linear CO dynamics. Therefore, it has to be taken into account, that V˙O2pulm may not be a valuable surrogate for muscular oxygen uptake kinetics in the recovery phases.
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Affiliation(s)
- U Drescher
- Institute of Physiology and Anatomy, Am Sportpark Müngersdorf 6, German Sport University Cologne, Cologne, 50933, Germany.
| | - S Mookerjee
- Department of Exercise Science, 400 E. 2nd St, Bloomsburg University, Bloomsburg, PA, 17815, USA
| | - A Steegmanns
- Institute of Physiology and Anatomy, Am Sportpark Müngersdorf 6, German Sport University Cologne, Cologne, 50933, Germany
| | - A Knicker
- Institute of Movement and Neuroscience, Am Sportpark Müngersdorf 6, German Sport University Cologne, Cologne, 50933, Germany
| | - U Hoffmann
- Institute of Physiology and Anatomy, Am Sportpark Müngersdorf 6, German Sport University Cologne, Cologne, 50933, Germany
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10
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Poole DC, Burnley M, Vanhatalo A, Rossiter HB, Jones AM. Critical Power: An Important Fatigue Threshold in Exercise Physiology. Med Sci Sports Exerc 2016; 48:2320-2334. [PMID: 27031742 PMCID: PMC5070974 DOI: 10.1249/mss.0000000000000939] [Citation(s) in RCA: 309] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
: The hyperbolic form of the power-duration relationship is rigorous and highly conserved across species, forms of exercise, and individual muscles/muscle groups. For modalities such as cycling, the relationship resolves to two parameters, the asymptote for power (critical power [CP]) and the so-called W' (work doable above CP), which together predict the tolerable duration of exercise above CP. Crucially, the CP concept integrates sentinel physiological profiles-respiratory, metabolic, and contractile-within a coherent framework that has great scientific and practical utility. Rather than calibrating equivalent exercise intensities relative to metabolically distant parameters such as the lactate threshold or V˙O2max, setting the exercise intensity relative to CP unifies the profile of systemic and intramuscular responses and, if greater than CP, predicts the tolerable duration of exercise until W' is expended, V˙O2max is attained, and intolerance is manifested. CP may be regarded as a "fatigue threshold" in the sense that it separates exercise intensity domains within which the physiological responses to exercise can (CP) be stabilized. The CP concept therefore enables important insights into 1) the principal loci of fatigue development (central vs. peripheral) at different intensities of exercise and 2) mechanisms of cardiovascular and metabolic control and their modulation by factors such as O2 delivery. Practically, the CP concept has great potential application in optimizing athletic training programs and performance as well as improving the life quality for individuals enduring chronic disease.
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Affiliation(s)
- David C. Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas, U.S.A
| | - Mark Burnley
- School of Sport and Exercise Sciences, University of Kent, Chatham, U.K
| | - Anni Vanhatalo
- Sport and Health Sciences, St. Luke’s Campus, University of Exeter, Exeter, U.K
| | - Harry B. Rossiter
- Faculty of Biological Sciences University of Leeds, Leeds, U.K
- Rehabilitaion Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, U.S.A
| | - Andrew M. Jones
- Sport and Health Sciences, St. Luke’s Campus, University of Exeter, Exeter, U.K
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11
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Fukuoka Y, Poole DC, Barstow TJ, Kondo N, Nishiwaki M, Okushima D, Koga S. Reduction of V̇O2 slow component by priming exercise: novel mechanistic insights from time-resolved near-infrared spectroscopy. Physiol Rep 2015; 3:3/6/e12432. [PMID: 26109190 PMCID: PMC4510633 DOI: 10.14814/phy2.12432] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Novel time-resolved near-infrared spectroscopy (TR-NIRS), with adipose tissue thickness correction, was used to test the hypotheses that heavy priming exercise reduces the V̇O2 slow component (V̇O2SC) (1) by elevating microvascular [Hb] volume at multiple sites within the quadriceps femoris (2) rather than reducing the heterogeneity of muscle deoxygenation kinetics. Twelve subjects completed two 6-min bouts of heavy work rate exercise, separated by 6 min of unloaded cycling. Priming exercise induced faster overall V̇O2 kinetics consequent to a substantial reduction in the V̇O2SC (0.27 ± 0.12 vs. 0.11 ± 0.09 L·min−1, P < 0.05) with an unchanged primary V̇O2 time constant. An increased baseline for the primed bout [total (Hb + Mb)] (197.5 ± 21.6 vs. 210.7 ± 22.5 μmol L−1, P < 0.01), reflecting increased microvascular [Hb] volume, correlated significantly with the V̇O2SC reduction. At multiple sites within the quadriceps femoris, priming exercise reduced the baseline and slowed the increase in [deoxy (Hb + Mb)]. Changes in the intersite coefficient of variation in the time delay and time constant of [deoxy (Hb + Mb)] during the second bout were not correlated with the V̇O2SC reduction. These results support a mechanistic link between priming exercise-induced increase in muscle [Hb] volume and the reduced V̇O2SC that serves to speed overall V̇O2 kinetics. However, reduction in the heterogeneity of muscle deoxygenation kinetics does not appear to be an obligatory feature of the priming response.
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Affiliation(s)
- Yoshiyuki Fukuoka
- Environmental Physiology Laboratory, Prefectural University of Kumamoto, Kumamoto, Japan Graduate School of Health and Sports Science, Doshisha University, Kyoto, Japan
| | - David C Poole
- Departments of Anatomy and Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Thomas J Barstow
- Departments of Anatomy and Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Narihiko Kondo
- Graduate School of Cultural Studies and Human Science, Kobe University, Kobe, Japan
| | - Masato Nishiwaki
- Faculty of Engineering, Osaka Institute of Technology, Osaka, Japan
| | - Dai Okushima
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
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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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Bopp CM, Townsend DK, Warren S, Barstow TJ. Relationship between brachial artery blood flow and total [hemoglobin+myoglobin] during post-occlusive reactive hyperemia. Microvasc Res 2014; 91:37-43. [DOI: 10.1016/j.mvr.2013.10.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 10/23/2013] [Accepted: 10/24/2013] [Indexed: 10/26/2022]
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Abstract
Muscular exercise requires transitions to and from metabolic rates often exceeding an order of magnitude above resting and places prodigious demands on the oxidative machinery and O2-transport pathway. The science of kinetics seeks to characterize the dynamic profiles of the respiratory, cardiovascular, and muscular systems and their integration to resolve the essential control mechanisms of muscle energetics and oxidative function: a goal not feasible using the steady-state response. Essential features of the O2 uptake (VO2) kinetics response are highly conserved across the animal kingdom. For a given metabolic demand, fast VO2 kinetics mandates a smaller O2 deficit, less substrate-level phosphorylation and high exercise tolerance. By the same token, slow VO2 kinetics incurs a high O2 deficit, presents a greater challenge to homeostasis and presages poor exercise tolerance. Compelling evidence supports that, in healthy individuals walking, running, or cycling upright, VO2 kinetics control resides within the exercising muscle(s) and is therefore not dependent upon, or limited by, upstream O2-transport systems. However, disease, aging, and other imposed constraints may redistribute VO2 kinetics control more proximally within the O2-transport system. Greater understanding of VO2 kinetics control and, in particular, its relation to the plasticity of the O2-transport/utilization system is considered important for improving the human condition, not just in athletic populations, but crucially for patients suffering from pathologically slowed VO2 kinetics as well as the burgeoning elderly population.
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Affiliation(s)
- David C Poole
- Departments of Kinesiology, Anatomy, and Physiology, Kansas State University, Manhattan, Kansas, USA.
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Boone J, Celie B, Dumortier J, Barstow TJ, De Bleecker J, Smet J, Van Lander A, Van Coster R, Bourgois J. Forearm muscle oxygenation responses during and following arterial occlusion in patients with mitochondrial myopathy. Respir Physiol Neurobiol 2013; 190:70-5. [PMID: 24070894 DOI: 10.1016/j.resp.2013.09.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 08/12/2013] [Accepted: 09/16/2013] [Indexed: 01/08/2023]
Abstract
The aim was to study whether mitochondrial myopathy induces different oxygenation (deoxy[Hb+Mb] and oxy[Hb+Mb]) responses during and following arterial occlusion. In 10 mitochondrial myopathy patients (MMpatients) (age: 29±7 years; body mass: 59.9±15.7kg; heigth: 166.2±11.4cm) and age- and gender-matched healthy subjects (age: 28±9 years; body mass: 72.7±16.9kg; height: 174.4±8.7cm) arterial occlusion was performed by inflating a cuff to 240mmHg. Deoxy[Hb+Mb] and oxy[Hb+Mb] were registered during (AOoxy and AOdeoxy) and following (POdeoxy and POoxy) arterial occlusion. Amplitude of AOdeoxy did not differ (p=0.47) between MMpatients (44.9±28.0μM) and healthy subjects (38.6±22.8μM), The time constant of the exponential model was greater in MMpatients (263.4±49.1s vs. 200.3±73.7s, p=0.03). Following cuff release, in both populations a transient increase in total[Hb+Mb] was observed induced by different kinetics of POoxy and POdeoxy. The increase in POoxy (TD=6.6±2.2s and 11.9±3.5s; τ=3.8±1.4s and 6.4±2.9s for MMpatients and healthy subjects, respectively) was faster (p<0.001 for TD and τ) compared to the decrease in POdeoxy (TD=13.2±3.6s and 26.5±4.6s; τ=-6.2±2.2s and -9.6±2.4s for MMpatients and healthy subjects, respectively). POoxy and POdeoxy showed faster kinetics (p<0.001 and p<0.01 for TD and τ, respectively) in MMpatients compared to healthy subjects. MMpatients display altered oxygenation responses during and following arterial occlusion reflecting pathology related changes in the relationship between muscle blood flow and oxygen uptake.
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Affiliation(s)
- Jan Boone
- Department of Movement and Sport Sciences, Ghent University, Watersportlaan 2, 9000 Ghent, Belgium; Center of Sports Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
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Hosokawa S, Koseki H, Nagashima M, Maeyama Y, Yomogida K, Mehr C, Rutledge M, Greenfeld H, Kaneki M, Tompkins RG, Martyn JAJ, Yasuhara SE. Title efficacy of phosphodiesterase 5 inhibitor on distant burn-induced muscle autophagy, microcirculation, and survival rate. Am J Physiol Endocrinol Metab 2013; 304:E922-33. [PMID: 23512808 DOI: 10.1152/ajpendo.00078.2013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Skeletal muscle wasting is an exacerbating factor in the prognosis of critically ill patients. Using a systemic burn injury model in mice, we have established a role of autophagy in the resulting muscle wasting that is distant from the burn trauma. We provide evidence that burn injury increases the autophagy turnover in the distal skeletal muscle by conventional postmortem tissue analyses and by a novel in vivo microscopic method using an autophagy reporter gene (tandem fluorescent LC3). The effect of tadalafil, a phosphodiesterase 5 inhibitor (PDE5I), on burn-induced skeletal muscle autophagy is documented and extends our published results that PDE5Is attenuates muscle degeneration in a muscular dystrophy model. We also designed a translational experiment to examine the impact of PDE5I on whole body and demonstrated that PDE5I administration lessened muscle atrophy, mitigated microcirculatory disturbance, and improved the survival rate after burn injury.
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Affiliation(s)
- Sachiko Hosokawa
- Department of Anesthesiology and Critical Care and Pain Medicine, Shriners Hospital for Children, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
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Mesquita RC, Putt M, Chandra M, Yu G, Xing X, Han SW, Lech G, Shang Y, Durduran T, Zhou C, Yodh AG, Mohler ER. Diffuse optical characterization of an exercising patient group with peripheral artery disease. JOURNAL OF BIOMEDICAL OPTICS 2013; 18:57007. [PMID: 23708193 PMCID: PMC3662991 DOI: 10.1117/1.jbo.18.5.057007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 04/07/2013] [Accepted: 04/19/2013] [Indexed: 05/19/2023]
Abstract
Peripheral artery disease (PAD) is a common condition with high morbidity. While measurement of tissue oxygen saturation (S(t)O(2)) has been demonstrated, this is the first study to assess both S(t)O(2) and relative blood flow (rBF) in the extremities of PAD patients. Diffuse optics is employed to measure hemodynamic response to treadmill and pedal exercises in 31 healthy controls and 26 patients. For S(t)O(2), mild and moderate/severe PAD groups show pronounced differences compared with controls. Pre-exercise mean S(t)O(2) is lower in PAD groups by 9.3% to 10.6% compared with means of 63.5% to 66.2% in controls. For pedal, relative rate of return of S(t)O(2) to baseline is more rapid in controls (p < 0.05). Patterns of rBF also differ among groups. After both exercises, rBF tend to occur at depressed levels among severe PAD patients compared with healthy (p < 0.05); post-treadmill, rBF tend to occur at elevated levels among healthy compared with severe PAD patients (p < 0.05). Additionally, relative rate of return to baseline S(t)O(2) is more rapid among subjects with reduced levels of depression in rBF (p = 0.041), even after adjustment for ankle brachial index. This suggests a physiologic connection between rBF and oxygenation that can be measured using diffuse optics, and potentially employed as an evaluative tool in further studies.
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Affiliation(s)
- Rickson C Mesquita
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, PA 19104, USA.
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Fujino H, Kondo H, Murakami S, Nagatomo F, Fujita N, Takeda I, Ishihara A, Roy RR. Differences in capillary architecture, hemodynamics, and angiogenic factors in rat slow and fast plantarflexor muscles. Muscle Nerve 2012; 45:242-9. [PMID: 22246881 DOI: 10.1002/mus.22267] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
INTRODUCTION The capillary architecture in skeletal muscles is unique in that it has anastomoses that interconnect individual capillaries. METHODS We used new techniques to measure velocity of red blood cells (V(RBC) ) in both capillaries and anastomoses in situ. The volume of capillaries/anastomoses was determined, and the levels of several angiogenic regulators were compared between the soleus and the superficial gastrocnemius (LG(sup) ). RESULTS The V(RBC) in both capillaries and anastomoses was slower in soleus than in LG(sup) . The numbers of capillaries and anastomoses were higher, diameter of capillaries smaller, and tortuosity greater in soleus than in LG(sup) . Consequently, the capillary/anastomoses volume was larger in soleus than in LG(sup) . Furthermore, several angiogenic regulators (HIF-1α, VEGF, Flt-1, KDR, angiopoietin-1 and -2, and Tie-2) were higher in soleus than in LG(sup) . CONCLUSION The differences in microvascular architecture, V(RBC) , and levels of angiogenic regulators between soleus and LG(sup) reflect the greater oxygen demands of the highly active soleus muscle.
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Affiliation(s)
- Hidemi Fujino
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-Ku, Kobe 654-0142, Japan.
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Belfry GR, Paterson DH, Murias JM, Thomas SG. The effects of short recovery duration on VO2 and muscle deoxygenation during intermittent exercise. Eur J Appl Physiol 2011; 112:1907-15. [PMID: 21927832 DOI: 10.1007/s00421-011-2152-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 08/25/2011] [Indexed: 11/28/2022]
Abstract
This study compared the oxygen uptake (VO(2)) and muscle deoxygenation (∆HHb) of two intermittent protocols to responses during continuous constant load cycle exercise in males (24 year ± 2, n = 7). Subjects performed three protocols: (1) 10 s work/5 s active recovery (R), R at 20 W (INT1): (2) 10 s work/5 s R, R at moderate intensity (INT2); and (3) continuous exercise (CONT), all for 10 min, on separate days. The work rate of CONT and the 10 s work of INT1 and INT2 were set within the heavy intensity domain. VO(2) and ∆HHb data were filtered and averaged to 5 s bins. Average VO(2) (80-420 s) was highest during CONT (3.77 L/min), lower in INT2 (3.04 L/min), and lowest during INT1 (2.81 L/min), all (p < 0.05). Average ∆HHb (80-420 s) was higher during CONT (p < 0.05) than both INT exercise protocols (CONT; 25.7 ± 0.9 a.u. INT1; 16.4 ± 0.8 a.u., and INT2; 15.8 ± 0.8 a.u.). The repeated changes in metabolic rate elicited oscillations in ΔHHb in both intermittent protocols, whereas oscillations in VO(2) were only observed during INT1. The greater ΔHHb during CONT suggests a reduction in oxygen delivery compared to oxygen consumption relative to INT. The higher VO(2) for INT 2 versus INT 1 and similar ΔHHb during INT suggests an increase in oxygen delivery during INT 2. Thus the different demands of INT1, INT2, and CONT protocols elicited differing physiological responses to a similar heavy intensity power output. These intermittent exercise models seem to elicit an elevated O(2) delivery condition compared to CONT.
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Affiliation(s)
- Glen R Belfry
- Faculty of Health Sciences, School of Kinesiology, University of Western Ontario, Thames Hall, London, ON N6A 3K7, Canada.
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Hirai DM, Copp SW, Ferreira LF, Musch TI, Poole DC. Nitric oxide bioavailability modulates the dynamics of microvascular oxygen exchange during recovery from contractions. Acta Physiol (Oxf) 2010; 200:159-69. [PMID: 20384595 DOI: 10.1111/j.1748-1716.2010.02137.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIM lowered microvascular PO(2) (PO(2) mv) during the exercise off-transient likely impairs muscle metabolic recovery and limits the capacity to perform repetitive tasks. The current investigation explored the impact of altered nitric oxide (NO) bioavailability on PO(2) mv during recovery from contractions in healthy skeletal muscle. We hypothesized that increased NO bioavailability (sodium nitroprusside: SNP) would enhance PO(2) mv and speed its recovery kinetics while decreased NO bioavailability (l-nitro arginine methyl ester: l-NAME) would reduce PO(2) mv and slow its recovery kinetics. METHODS PO(2) mv was measured by phosphorescence quenching during transitions (rest-1 Hz twitch-contractions for 3 min-recovery) in the spinotrapezius muscle of Sprague-Dawley rats under SNP (300 microm), Krebs-Henseleit (CONTROL) and l-NAME (1.5 mm) superfusion conditions. RESULTS relative to recovery in CONTROL, SNP resulted in greater overall microvascular oxygenation as assessed by the area under the PO(2) mv curve (PO(2 AREA) ; CONTROL 3471 ± 292 mmHg s; SNP: 4307 ± 282 mmHg s; P < 0.05) and faster off-kinetics as evidenced by the mean response time (MRToff; CONTROL 60.2 ± 6.9 s; SNP: 34.8 ± 5.7 s; P < 0.05), whereas l-NAME produced lower PO(2 AREA) (2339 ± 444 mmHg s; P < 0.05) and slower MRToff (86.6 ± 14.5s; P < 0.05). CONCLUSION no bioavailability plays a key role in determining the matching of O(2) delivery-to-O(2) uptake and thus the upstream O(2) pressure driving capillary-myocyte O(2) flux (i.e. PO(2) mv) following cessation of contractions in healthy skeletal muscle. Additionally, these data support a mechanistic link between reduced NO bioavailability and prolonged muscle metabolic recovery commonly observed in ageing and diseased populations.
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Affiliation(s)
- D M Hirai
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506-5802, USA
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Copp SW, Hirai DM, Hageman KS, Poole DC, Musch TI. Nitric oxide synthase inhibition during treadmill exercise reveals fiber-type specific vascular control in the rat hindlimb. Am J Physiol Regul Integr Comp Physiol 2009; 298:R478-85. [PMID: 20007515 DOI: 10.1152/ajpregu.00631.2009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The control of vascular tone during exercise is highly complex and integrated. Specifically, in regards to the contribution of nitric oxide (NO), the observed magnitude and muscle fiber-type dependency of the NO contribution to exercise hyperemia may differ depending on the timing of NO synthase (NOS) inhibition with respect to the exercise bout (i.e., administration prior to vs. during exercise). We tested the hypothesis that, in the presence of prior cyclooxygenase inhibition (indomethacin, 5 mg/kg(-1)), NOS inhibition (N(G)-nitro-L-arginine methyl ester, L-NAME; 10 mg/kg) administered during submaximal treadmill exercise would blunt blood flow and vascular conductance (VC) in the hindlimb muscle(s) of the rat with the greatest reductions in blood flow and VC occurring in the predominantly oxidative muscles. Adult female Wistar rats (n = 10, age: 3-4 mo) ran on a motor-driven treadmill (20 m/min, 10% grade). Total and regional hindlimb muscle blood flow and VC were determined via radiolabeled microspheres before (control) and after L-NAME administration during exercise. L-NAME reduced (P < 0.05) total hindlimb muscle blood flow (control: 123 + or - 10, L-NAME: 103 + or - 7 ml x min(-1) x 100g(-1)) and VC (control: 0.95 + or - 0.09, L-NAME: 0.63 + or - 0.05 ml x min(-1) x 100g(-1) x mmHg(-1)). There was a significant correlation (r = 0.51, P < 0.05) between the absolute reductions in VC after L-NAME and the percent sum of type I and IIa fibers in the individual muscles and muscle parts; however, there was no correlation (P = 0.62) when expressed as blood flow. Surprisingly, the highly oxidative muscles demonstrated a marked ability to maintain oxygen delivery, which differs substantially from previous reports of L-NAME infusion prior to exercise in these muscles. The demonstration that NO is an important regulator of blood flow and VC in the rat hindlimb during treadmill exercise, but that the fiber-type dependency of NO is altered markedly when NOS inhibition is performed during, vs. prior to, exercise, lends important insights into the integrated nature of vascular control during exercise.
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Affiliation(s)
- Steven W Copp
- Department of Kinesiology, Kansas State University, Manhattan, Kansas, USA
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Aging impacts microvascular oxygen pressures during recovery from contractions in rat skeletal muscle. Respir Physiol Neurobiol 2009; 169:315-22. [PMID: 19833236 DOI: 10.1016/j.resp.2009.10.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Revised: 09/28/2009] [Accepted: 10/06/2009] [Indexed: 11/20/2022]
Abstract
Aging-induced alterations in peripheral circulatory control during contractions reduce the microvascular partial pressure of O(2) (P(O)(2)mv; which reflects the dynamic balance in the O(2) delivery-to-O(2) uptake ratio), resulting in exaggerated intramuscular metabolic disturbances and premature fatigue. However, the extent to which this altered P(O)(2)mv during contractions is associated with prolongated muscle metabolic recovery is not known. We tested the hypothesis that the aging-induced speeding of the P(O)(2)mv on-kinetics would presage slowed P(O)(2)mv off-kinetics. The spinotrapezius muscle was exposed in six young (6-8 months) and seven old (26-28 months) male Fischer 344xBrown Norway F1-hybrid rats. The P(O)(2)mv kinetic profile was measured via phosphorescence quenching at rest, during electrically stimulated contractions (1Hz, 7-9V, 2ms pulse duration, 180s), and throughout recovery (180s). Aged rats which evidenced faster P(O)(2)mv on-kinetics (reduced mean response time (MRTon), young: 27.3+/-3.6s, old: 19.2+/-1.6s; P<0.05) exhibited markedly slowed P(O)(2)mv off-kinetics (increased MRToff, young: 46.5+/-5.9s, old: 84.8+/-7.9s; P<0.05). Accordingly, a greater degree of P(O)(2)mv on-off asymmetry (MRToff-MRTon) in the aged muscle was observed (young: 19.1+/-4.5s, old: 65.6+/-8.6s; P<0.01). We conclude that aging-induced speeding of the P(O)(2)mv on-kinetics does indeed presage a slowed P(O)(2)mv off-kinetics, which likely compromises muscle metabolic recovery and may reduce subsequent contractile performance. Moreover, the greater degree of P(O)(2)mv on-off asymmetry in the aged muscle suggests a mechanistic link between impaired microvascular oxygenation and altered muscle metabolic responses during exercise transitions.
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Behnke BJ, Ferreira LF, McDonough PJ, Musch TI, Poole DC. Recovery dynamics of skeletal muscle oxygen uptake during the exercise off-transient. Respir Physiol Neurobiol 2009; 168:254-60. [PMID: 19619675 DOI: 10.1016/j.resp.2009.07.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 07/10/2009] [Accepted: 07/13/2009] [Indexed: 11/26/2022]
Abstract
UNLABELLED The time course of muscle .V(O2) recovery from contractions (i.e., muscle .V(O2) off-kinetics), measured directly at the site of O(2) exchange, i.e., in the microcirculation, is unknown. Whereas biochemical models based upon creatine kinase flux rates predict slower .V(O2) off- than on-transients [Kushmerick, M.J., 1998. Comp. Biochem. Physiol. B: Biochem. Mol. Biol.], whole muscle .V(O2) data [Krustrup, et al. J. Physiol.] suggest on-off symmetry. PURPOSE We tested the hypothesis that the slowed recovery blood flow (Qm) kinetics profile in the spinotrapezius muscle [Ferreira et al., 2006. J. Physiol.] was associated with a slowed muscle .V(O2) recovery compared with that seen at the onset of contractions (time constant, tau approximately 23s, Behnke et al., 2002. Resp. Physiol.), i.e., on-off asymmetry. METHODS Measurements of capillary red blood cell flux and microvascular pressure of O(2) (P(O2) mv) were combined to resolve the temporal profile of muscle .V(O2) across the moderate intensity contractions-to-rest transition. RESULTS Muscle .V(O2) decreased from an end-contracting value of 7.7+/-0.2 ml/100 g/min to 1.7+/-0.1 ml/100g/min at the end of the 3 min recovery period, which was not different from pre-stimulation .V(O2). Contrary to our hypothesis, muscle .V(O2) in recovery began to decrease immediately (i.e., time delay <2s) and demonstrated rapid first-order kinetics (tau, 25.5+/-2.6s) not different (i.e., symmetrical to) to those during the on-transient. This resulted in a systematic increase in microvascular P(O2) during the recovery from contractions. CONCLUSIONS The slowed Qm kinetics in recovery serves to elevate the Qm/.V(O2) ratio and thus microvascular P(O2) . Whether this Qm response is obligatory to the rapid muscle .V(O2) kinetics and hence speeds the repletion of high-energy phosphates by maximizing conductive and diffusive O(2) flux is an important question that awaits resolution.
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Affiliation(s)
- Brad J Behnke
- Department of Applied Physiology & Kinesiology, University of Florida, Gainesville, FL 32611, USA.
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Gelman S, De Backer D, Koch M, Vincent JL. Is a decrease in capillary density dangerous? Br J Anaesth 2009; 102:561; author reply 561. [DOI: 10.1093/bja/aep027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Erythrocyte flow in choriocapillaris of normal and diabetic rats. Microvasc Res 2009; 77:247-55. [PMID: 19269298 DOI: 10.1016/j.mvr.2009.02.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 02/13/2009] [Accepted: 02/25/2009] [Indexed: 11/23/2022]
Abstract
The choriocapillaris is a unique capillary bed that provides nutrients to the retinal photoreceptors. It changes anatomically in diabetes, but the impact of these changes on blood flow is unknown. In this study hemodynamic parameters in individual choriocapillaris vessels were compared in normal and diabetic rats. Three groups were studied: normal buffer-injected control rats, streptozotocin (STZ)-injected mildly hyperglycemic (STZ-MH) rats, and STZ-injected diabetic (STZ-D) rats. 7-8 weeks after STZ injection, the rats were anesthetized, and epifluorescent, intravital microscopy was used to record the flow of fluorescent red blood cells (RBC) in the choriocapillaris. Diameter, RBC flux, and RBC velocity were measured in 153 capillary pathways in five control rats, 98 pathways in four STZ-MH rats, and 153 pathways in seven STZ-D rats. There was no difference in capillary diameter among the groups. RBC flux and velocity were lower in the STZ-injected rats compared to the controls (p<or=0.023), which is similar to changes found in other capillary beds. RBC velocity and flux were significantly correlated in all three groups, but the correlations in the STZ-injected rats were much stronger than in the controls. This indicates a more heterogeneous distribution of RBCs at upstream arteriolar branch points in hyperglycemic rats, which could lead to a decrease in choriocapillaris hematocrit. These changes in the hyperglycemic choriocapillaris could contribute to impaired oxygen delivery to the photoreceptors in diabetic retina.
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VanTeeffelen JWGE, Constantinescu AA, Brands J, Spaan JAE, Vink H. Bradykinin- and sodium nitroprusside-induced increases in capillary tube haematocrit in mouse cremaster muscle are associated with impaired glycocalyx barrier properties. J Physiol 2008; 586:3207-18. [PMID: 18450777 DOI: 10.1113/jphysiol.2008.152975] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Previous studies have suggested that agonists may increase functionally perfused capillary volume by modulation of blood-excluding glycocalyx volume, but direct evidence for this association is lacking at the moment. Using intravital microscopic visualization of mouse cremaster muscle, we determined the effects of bradykinin (10(-5) M) and sodium nitroprusside (10(-6) M) on capillary tube haematocrit and glycocalyx barrier properties. In control C57Bl/6 mice (n = 10), tube haematocrit in capillaries (n = 71) increased (P < 0.05) from 8.7 +/- 0.3% during baseline to 21.2 +/- 1.2 and 22.2 +/- 0.9% during superfusion with bradykinin and nitroprusside, respectively. In parallel, the exclusion zone of FITC-labelled 70 kDa dextrans decreased (P < 0.05) from 0.37 +/- 0.01 microm during baseline to 0.17 +/- 0.01 microm with bradykinin and 0.15 +/- 0.01 microm with nitroprusside. Bradykinin and nitroprusside had no effect on dextran exclusion and tube haematocrit in capillaries (n = 55) of hyperlipidemic ApoE3-Leiden mice, which showed impaired exclusion of 70 kDa dextrans (0.05 +/- 0.02 microm; P < 0.05 versus C57Bl/6) and increased capillary tube haematocrit (23 +/- 0.8%; P < 0.05 versus C57Bl/6) under baseline conditions, indicating glycocalyx degradation. Our data show that vasodilator substances increase functionally perfused capillary volume and that this effect is associated with a reduction in glycocalyx exclusion of 70 kDa dextrans. Modulation of glycocalyx volume might represent a novel mechanism of perfusion control at the capillary level.
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Affiliation(s)
- Jurgen W G E VanTeeffelen
- Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands.
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Lutjemeier BJ, Ferreira LF, Poole DC, Townsend D, Barstow TJ. Muscle microvascular hemoglobin concentration and oxygenation within the contraction-relaxation cycle. Respir Physiol Neurobiol 2007; 160:131-8. [PMID: 17964228 DOI: 10.1016/j.resp.2007.09.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Revised: 08/24/2007] [Accepted: 09/11/2007] [Indexed: 12/01/2022]
Abstract
Inability to directly measure microvascular oxygen distribution and extraction in striated muscle during a contraction/relaxation cycle limits our understanding of oxygen transport to and utilization by contracting muscle. We examined muscle microvascular hemoglobin concentration (total [Hb/Mb]) and oxygenation within the contraction-relaxation cycle to determine if microvascular RBC volume would be preserved and if oxygen extraction continued during the actual contraction phase. Eight subjects performed dynamic knee extension exercise (40 contractions/min) at moderate ( approximately 30% of peak work rate) and heavy ( approximately 80% of peak) work rates. Total hemoglobin/myoglobin (total [Hb/Mb]) and deoxy-hemoglobin/myoglobin (deoxy-[Hb/Mb]) were measured in the rectus femoris using NIRS to determine if microvascular total [Hb/Mb] would be preserved during the contraction, and to estimate microvascular oxygen extraction, respectively. Mean values during the relaxation (RP) and contractile phases and the peak values during the contractile phase for both moderate and heavy exercise were calculated. Total [Hb/Mb] increased from rest to steady-state exercise (6.36+/-5.08 microM moderate; 5.72+/-4.46 microM heavy exercise, both P<0.05), but did not change significantly within the contraction/relaxation cycle. Muscle contractions were associated with a significant (1.29+/-0.98 microM moderate; 2.16+/-2.12 microM heavy exercise, P<0.05) increase in deoxy-[Hb/Mb] relative to RP. We conclude that (a) microvascular RBC volume is preserved during muscle contractions (i.e., RBCs are present in the capillaries), and (b) the cyclical pattern of deoxygenation/oxygenation during the respective contraction/relaxation phases of the contraction cycle suggests that oxygen extraction is not restricted to the relaxation phase but continues to occur during muscle contractions.
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Affiliation(s)
- Barbara J Lutjemeier
- Department of Kinesiology, Kansas State University, Manhattan, KS 66506-0302, USA
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Asai A, Sahani N, Kaneki M, Ouchi Y, Martyn JJ, Yasuhara SE. Primary role of functional ischemia, quantitative evidence for the two-hit mechanism, and phosphodiesterase-5 inhibitor therapy in mouse muscular dystrophy. PLoS One 2007; 2:e806. [PMID: 17726536 PMCID: PMC1950086 DOI: 10.1371/journal.pone.0000806] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Accepted: 07/25/2007] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Duchenne Muscular Dystrophy (DMD) is characterized by increased muscle damage and an abnormal blood flow after muscle contraction: the state of functional ischemia. Until now, however, the cause-effect relationship between the pathogenesis of DMD and functional ischemia was unclear. We examined (i) whether functional ischemia is necessary to cause contraction-induced myofiber damage and (ii) whether functional ischemia alone is sufficient to induce the damage. METHODOLOGY/PRINCIPAL FINDINGS In vivo microscopy was used to document assays developed to measure intramuscular red blood cell flux, to quantify the amount of vasodilatory molecules produced from myofibers, and to determine the extent of myofiber damage. Reversal of functional ischemia via pharmacological manipulation prevented contraction-induced myofiber damage in mdx mice, the murine equivalent of DMD. This result indicates that functional ischemia is required for, and thus an essential cause of, muscle damage in mdx mice. Next, to determine whether functional ischemia alone is enough to explain the disease, the extent of ischemia and the amount of myofiber damage were compared both in control and mdx mice. In control mice, functional ischemia alone was found insufficient to cause a similar degree of myofiber damage observed in mdx mice. Additional mechanisms are likely contributing to cause more severe myofiber damage in mdx mice, suggestive of the existence of a "two-hit" mechanism in the pathogenesis of this disease. CONCLUSIONS/SIGNIFICANCE Evidence was provided supporting the essential role of functional ischemia in contraction-induced myofiber damage in mdx mice. Furthermore, the first quantitative evidence for the "two-hit" mechanism in this disease was documented. Significantly, the vasoactive drug tadalafil, a phosphodiesterase 5 inhibitor, administered to mdx mice ameliorated muscle damage.
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Affiliation(s)
- Akihiro Asai
- Department of Anesthesiology and Critical Care, Shriners Hospital for Children, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Geriatric Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Nita Sahani
- Department of Anesthesiology and Critical Care, Shriners Hospital for Children, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Masao Kaneki
- Department of Anesthesiology and Critical Care, Shriners Hospital for Children, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yasuyoshi Ouchi
- Department of Geriatric Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - J.A. Jeevendra Martyn
- Department of Anesthesiology and Critical Care, Shriners Hospital for Children, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Shingo Egusa Yasuhara
- Department of Anesthesiology and Critical Care, Shriners Hospital for Children, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- * To whom correspondence should be addressed. E-mail:
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Burnley M, Doust JH, Jones AM. Time required for the restoration of normal heavy exercise VO2 kinetics following prior heavy exercise. J Appl Physiol (1985) 2006; 101:1320-7. [PMID: 16857864 DOI: 10.1152/japplphysiol.00475.2006] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Prior heavy exercise markedly alters the O2 uptake (VO2) response to subsequent heavy exercise. However, the time required for VO2 to return to its normal profile following prior heavy exercise is not known. Therefore, we examined the VO2 responses to repeated bouts of heavy exercise separated by five different recovery durations. On separate occasions, nine male subjects completed two 6-min bouts of heavy cycle exercise separated by 10, 20, 30, 45, or 60 min of passive recovery. The second-by-second VO2 responses were modeled using nonlinear regression. Prior heavy exercise had no effect on the primary VO2 time constant (from 25.9 +/- 4.7 s to 23.9 +/- 8.8 s after 10 min of recovery; P = 0.338), but it increased the primary VO2 amplitude (from 2.42 +/- 0.39 to 2.53 +/- 0.41 l/min after 10 min of recovery; P = 0.001) and reduced the VO2 slow component (from 0.44 +/- 0.13 to 0.21 +/- 0.12 l/min after 10 min of recovery; P < 0.001). The increased primary amplitude was also evident after 20-45 min, but not after 60 min, of recovery. The increase in the primary VO2 amplitude was accompanied by an increased baseline blood lactate concentration (to 5.1 +/- 1.0 mM after 10 min of recovery; P < 0.001). Baseline blood lactate concentration was still elevated after 20-60 min of recovery. The priming effect of prior heavy exercise on the VO2 response persists for at least 45 min, although the mechanism underpinning the effect remains obscure.
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Affiliation(s)
- Mark Burnley
- Department of Sport and Exercise Science, University of Wales, Aberystwyth, Aberystwyth, Ceredigion SY23 3FD, UK.
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