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Kano R, Kusano T, Takeda R, Shirakawa H, Poole DC, Kano Y, Hoshino D. Eccentric contraction increases hydrogen peroxide levels and alters gene expression through Nox2 in skeletal muscle of male mice. J Appl Physiol (1985) 2024; 137:778-788. [PMID: 39052772 DOI: 10.1152/japplphysiol.00335.2024] [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: 05/07/2024] [Revised: 07/03/2024] [Accepted: 07/19/2024] [Indexed: 07/27/2024] Open
Abstract
Hydrogen peroxide (H2O2) is one of the key signaling factors regulating skeletal muscle adaptation to muscle contractions. Eccentric (ECC) and concentric (CONC) contractions drive different muscle adaptations with ECC resulting in greater changes. The present investigation tested the hypothesis that ECC produces higher cytosolic and mitochondrial H2O2 concentrations [H2O2] and alters gene expression more than CONC. Cytosolic and mitochondrial H2O2-sensitive fluorescent proteins, HyPer7 and MLS-HyPer7, were expressed in the anterior tibialis muscle of C57BL6J male mice. Before and for 60 min after either CONC or ECC (100 Hz, 50 contractions), [H2O2]cyto and [H2O2]mito were measured by in vivo fluorescence microscopy. RNA sequencing was performed in control (noncontracted), CONC, and ECC muscles to identify genes impacted by the contractions. [H2O2]cyto immediately after ECC was greater than after CONC (CONC: +6%, ECC: +11% vs. rest, P < 0.05) and remained higher for at least 60 min into recovery. In contrast, the elevation of [H2O2]mito was independent of the contraction modes (time; P < 0.0042, contraction mode; P = 0.4965). The impact of ECC on [H2O2]cyto was abolished by NADPH oxidase 2 (Nox2) inhibition (GSK2795039). Differentially expressed genes were not present after CONC or ECC + GSK but were found after ECC and were enriched for vascular development and apoptosis-related genes, among others. In conclusion, in mouse anterior tibialis, ECC, but not CONC, evokes a pronounced cytosolic H2O2 response, caused by Nox2, that is mechanistically linked to gene expression modifications.NEW & NOTEWORTHY This in vivo model successfully characterized the effects of eccentric (ECC) and concentric (CONC) contractions on cytosolic and mitochondrial [H2O2] in mouse skeletal muscle. Compared with CONC, ECC induced higher and more sustained [H2O2]cyto-an effect that was abolished by Nox2 inhibition. ECC-induced [H2O2]cyto elevations were requisite for altered gene expression.
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Affiliation(s)
- Ryotaro Kano
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Japan
- Research Fellowship for Young Scientists, Japan Society for the Promotion of Science, Chiyoda, Japan
| | - Tatsuya Kusano
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Japan
| | - Reo Takeda
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Japan
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Hideki Shirakawa
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Japan
| | - David C Poole
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas, United States
- Department of Kinesiology, Kansas State University, Manhattan, Kansas, United States
| | - Yutaka Kano
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Japan
- Center for Neuroscience and Biomedical Engineering (CNBE), University of Electro-Communications, Chofu, Japan
| | - Daisuke Hoshino
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Japan
- Center for Neuroscience and Biomedical Engineering (CNBE), University of Electro-Communications, Chofu, Japan
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Takamizawa R, Hotta K, Fujii Y, Ikegami R, Hitosugi N, Inoue T, Tamiya H, Tsubaki A. Transcapillary PO 2 Gradients in Contracting Muscles of Type I Diabetic Rats. Microcirculation 2024; 31:e12870. [PMID: 38805591 DOI: 10.1111/micc.12870] [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: 02/23/2024] [Revised: 05/04/2024] [Accepted: 05/13/2024] [Indexed: 05/30/2024]
Abstract
OBJECTIVE This study aimed to clarify the effect of Type I diabetes (DIA) on transcapillary PO2 gradients, which are oxygen-driving factors between the blood and the interstitium, in the contracting muscle of rats. METHODS Wistar male rats were divided into the diabetic (streptozocin i.p.) and sham groups. Microvascular and interstitial PO2 were measured in the extensor digitorum longus muscle during electrical stimulation-induced muscle contraction, using the phosphorescence quenching method. Transcapillary PO2 gradient, ΔPO2, was calculated as microvascular minus interstitial PO2. RESULTS Resting microvascular PO2 was higher in the diabetic group than in the sham group (6.3 ± 1.7 vs. 4.7 ± 0.9 mmHg, p < 0.05) and remained for 180 s. Interstitial PO2 from rest to muscle contraction did not differ between the groups. The ΔPO2 was higher in the diabetic group than in the sham group at rest and during muscle contraction (4.03 ± 1.42 vs. 2.46 ± 0.90 mmHg at rest; 3.67 ± 1.51 vs. 2.22 ± 0.65 mmHg during muscle contraction, p < 0.05). Marked muscle atrophy was observed in the diabetic group. CONCLUSION DIA increased microvascular and transcapillary PO2 gradients in the skeletal muscle. The enhanced PO2 gradients were maintained from rest to muscle contraction in diabetic muscle.
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Affiliation(s)
- Ren Takamizawa
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Niigata, Japan
| | - Kazuki Hotta
- Department of Rehabilitation, Kitasato University School of Allied Health Sciences, Sagamihara, Kanagawa, Japan
- Department of Rehabilitation Sciences, Kitasato University Graduate School of Medical Sciences, Sagamihara, Kanagawa, Japan
| | - Yutaka Fujii
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Niigata, Japan
| | - Ryo Ikegami
- Department of Engineering Science, University of Electro-Communications, Chofu, Tokyo, Japan
| | - Naoki Hitosugi
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Niigata, Japan
| | - Tatsuro Inoue
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Niigata, Japan
| | - Hajime Tamiya
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Niigata, Japan
| | - Atsuhiro Tsubaki
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Niigata, Japan
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Chatzinikolaou PN, Margaritelis NV, Paschalis V, Theodorou AA, Vrabas IS, Kyparos A, D'Alessandro A, Nikolaidis MG. Erythrocyte metabolism. Acta Physiol (Oxf) 2024; 240:e14081. [PMID: 38270467 DOI: 10.1111/apha.14081] [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: 07/03/2023] [Revised: 12/11/2023] [Accepted: 01/01/2024] [Indexed: 01/26/2024]
Abstract
Our aim is to present an updated overview of the erythrocyte metabolism highlighting its richness and complexity. We have manually collected and connected the available biochemical pathways and integrated them into a functional metabolic map. The focus of this map is on the main biochemical pathways consisting of glycolysis, the pentose phosphate pathway, redox metabolism, oxygen metabolism, purine/nucleoside metabolism, and membrane transport. Other recently emerging pathways are also curated, like the methionine salvage pathway, the glyoxalase system, carnitine metabolism, and the lands cycle, as well as remnants of the carboxylic acid metabolism. An additional goal of this review is to present the dynamics of erythrocyte metabolism, providing key numbers used to perform basic quantitative analyses. By synthesizing experimental and computational data, we conclude that glycolysis, pentose phosphate pathway, and redox metabolism are the foundations of erythrocyte metabolism. Additionally, the erythrocyte can sense oxygen levels and oxidative stress adjusting its mechanics, metabolism, and function. In conclusion, fine-tuning of erythrocyte metabolism controls one of the most important biological processes, that is, oxygen loading, transport, and delivery.
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Affiliation(s)
- Panagiotis N Chatzinikolaou
- Department of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, Serres, Greece
| | - Nikos V Margaritelis
- Department of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, Serres, Greece
| | - Vassilis Paschalis
- School of Physical Education and Sport Science, National and Kapodistrian University of Athens, Athens, Greece
| | - Anastasios A Theodorou
- Department of Life Sciences, School of Sciences, European University Cyprus, Nicosia, Cyprus
| | - Ioannis S Vrabas
- Department of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, Serres, Greece
| | - Antonios Kyparos
- Department of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, Serres, Greece
| | - Angelo D'Alessandro
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Michalis G Nikolaidis
- Department of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, Serres, Greece
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Hitosugi N, Hotta K, Taketa Y, Takamizawa R, Fujii Y, Ikegami R, Tamiya H, Inoue T, Tsubaki A. The effect of sepsis and reactive oxygen species on skeletal muscle interstitial oxygen pressure during contractions. Microcirculation 2024; 31:e12833. [PMID: 37800537 DOI: 10.1111/micc.12833] [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: 05/29/2023] [Revised: 09/09/2023] [Accepted: 09/23/2023] [Indexed: 10/07/2023]
Abstract
OBJECTIVE This study aims to examine the effect of sepsis on the dynamics of skeletal muscle partial oxygen pressure during muscle contractions as well as the effect of reactive oxygen species (ROS) scavenger (ascorbic acid, Asc). METHODS Twenty-seven male Sprague-Dawley rats (2-3 months old) were randomly assigned to three groups; sham, cecal ligation and puncture (CLP), or CLP plus ascorbic acid treatment group (CLP + Asc). Electrical stimuli-induced muscle contractions and partial oxygen pressure measurements were performed at 3 h after CLP. The interstitial oxygen pressure (PO2 is) in the spinotrapezius muscle was measured by the phosphorescence quenching method. RESULTS The PO2 is at rest was not different between the three groups. The PO2 is decreased from rest to contraction in all groups. Compared to the sham, the time to decrease PO2 is was significantly faster in CLP but not in CLP + Asc (p < .05). Compared to the sham, the PO2 is during muscle contractions was significantly lower in both CLP and CLP + Asc (p < .05, respectively). CONCLUSIONS Our results suggest that CLP-induced sepsis accelerated the decay of PO2 is at the onset of muscle contractions and maintained a low level of PO2 is during muscle contractions.
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Affiliation(s)
- Naoki Hitosugi
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
| | - Kazuki Hotta
- Department of Rehabilitation Sciences, Graduate School of Medical Sciences, Kitasato University, Sagamihara, Japan
- Department of Rehabilitation, Kitasato University School of Allied Health Sciences, Sagamihara, Japan
| | - Yoshikazu Taketa
- Department of Physical Therapy, Niigata University of Health and Welfare, Niigata, Japan
| | - Ren Takamizawa
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
| | - Yutaka Fujii
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
- Department of Clinical Engineering and Medical Technology, Niigata University of Health and Welfare, Niigata, Japan
| | - Ryo Ikegami
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
- Department of Physical Therapy, Niigata University of Health and Welfare, Niigata, Japan
| | - Hajime Tamiya
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
- Department of Physical Therapy, Niigata University of Health and Welfare, Niigata, Japan
| | - Tatsuro Inoue
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
- Department of Physical Therapy, Niigata University of Health and Welfare, Niigata, Japan
| | - Atsuhiro Tsubaki
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
- Department of Physical Therapy, Niigata University of Health and Welfare, Niigata, Japan
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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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Golub AS, Song BK, Nugent WH, Pittman RN. Dynamics of PO 2 and VO 2 in resting and contracting rat spinotrapezius muscle. Front Physiol 2023; 14:1172834. [PMID: 37538372 PMCID: PMC10396398 DOI: 10.3389/fphys.2023.1172834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 07/03/2023] [Indexed: 08/05/2023] Open
Abstract
This study examined changes in interstitial PO2, which allowed calculation of VO2 during periods of rest, muscle contraction and recovery using an in situ rat spinotrapezius muscle preparation. The PO2 was measured using phosphorescence quenching microscopy and the muscle VO2 was calculated as the rate of O2 disappearance during brief periods of muscle compression to stop blood flow with a supra-systolic pressure. The PO2 and VO2 measurements were made during "5 s compression and 15 s recovery" (CR) cycles. With all three stimulation frequencies, 1, 2 and 4 Hz, the fall in interstitial PO2 and rise in VO2 from resting values occurred within the first 20 s of contraction. The PO2 during contraction became lower as stimulation frequency increased from 1 to 4 Hz. VO2 was higher at 2 Hz than at 1 Hz contraction. With cessation of stimulation, PO2 began increasing exponentially towards baseline values. After 1 and 2 Hz contraction, the fall in muscle VO2 was delayed by one CR cycle and then exponentially decreased towards resting values. After 4 Hz stimulation, VO2 increased for 2 cycles and then decreased. The post-contraction transients of PO2 and VO2 were not synchronous and had different time constants. With further analysis two distinct functional responses were identified across all stimulation frequencies having PO2 during contraction above or below 30 mmHg. The corresponding VO2 responses were different - for "high" PO2, muscle VO2 reached high levels, while for the "low" PO2 data set muscle VO2 remained low. Recovery patterns were similar to those described above. In summary, local microscopic PO2 and VO2 were measured in resting and contracting muscle in situ and the post-contraction transients of PO2 and VO2 were all much slower than the onset transients.
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Affiliation(s)
- Aleksander S. Golub
- Department of Physiology and Biophysics, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, United States
- Song Biotechnologies LLC, Cockeysville, MD, United States
| | - Bjorn K. Song
- Department of Physiology and Biophysics, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, United States
- Song Biotechnologies LLC, Cockeysville, MD, United States
| | - William H. Nugent
- Department of Physiology and Biophysics, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, United States
- Song Biotechnologies LLC, Cockeysville, MD, United States
| | - Roland N. Pittman
- Department of Physiology and Biophysics, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, United States
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Koirala B, Concas A, Sun Y, Gladden LB, Lai N. Relationship between muscle venous blood oxygenation and near-infrared spectroscopy: quantitative analysis of the Hb and Mb contributions. J Appl Physiol (1985) 2023; 134:1063-1074. [PMID: 36927143 PMCID: PMC10125031 DOI: 10.1152/japplphysiol.00406.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 02/22/2023] [Accepted: 03/13/2023] [Indexed: 03/18/2023] Open
Abstract
A linear relationship between skeletal muscle venous ([Formula: see text]) and oxygenated (ΔHbMbO2,N) or deoxygenated (ΔHHbMbN) near-infrared spectroscopy (NIRS) signals suggest a main hemoglobin (Hb) contribution to the NIRS signal. However, experimental, and computational evidence supports a significant contribution of myoglobin (Mb) to the NIRS. Venous and NIRS measurements from a canine model of muscle oxidative metabolism (Sun Y, Ferguson BS, Rogatzki MJ, McDonald JR, Gladden LB. Med Sci Sports Exerc 48(10):2013-2020, 2016) were integrated into a computational model of muscle O2 transport and utilization to evaluate whether the relationship between venous and NIRS oxygenation can be affected by a significant Mb contribution to the NIRS signals. The mathematical model predicted well the measure of the changes of [Formula: see text] and NIRS signals for different O2 delivery conditions (blood flow, arterial O2 content) in muscle at rest (T1, T2) and during contraction (T3). Furthermore, computational analysis indicates that for adequate O2 delivery, Mb contribution to NIRS signals was significant (20%-30%) even in the presence of a linear [Formula: see text]-NIRS relationship; for a reduced O2 delivery the nonlinearity of the [Formula: see text]-NIRS relationship was related to the Mb contribution (50%). In this case (T3), the deviation from linearity is observed when O2 delivery is reduced from 1.3 to 0.7 L kg-1·min-1 ([Formula: see text] < 10 mLO2 100 mL-1) and Mb saturation decreased from 85% to 40% corresponding to an increase of the Mb contribution to ΔHHbMbN from 15% to 50% and the contribution to ΔHbMbO2,N from 0% to 30%. In contrast to a common assumption, our model indicates that both NIRS signals (ΔHHbMbN and ΔHbMbO2,N are significantly affected by Hb and Mb oxygenation changes.NEW & NOTEWORTHY Within the near-infrared spectroscopy (NIRS) signal, the contribution from hemoglobin is indistinguishable from that of myoglobin. A computation analysis indicates that a linear relationship between muscle venous oxygen content and NIRS signals does not necessarily indicate a negligible myoglobin contribution to the NIRS signal. A reduced oxygen delivery increases the myoglobin contribution to the NIRS signal. The integrative approach proposed is a powerful way to assist in interpreting the elements from which the NIRS signals are derived.
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Affiliation(s)
- Bhabuk Koirala
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia United States
- Biomedical Engineering Institute, Old Dominion University, Norfolk, Virginia, United States
| | - Alessandro Concas
- Department of Mechanical, Chemical and Materials Engineering, University of Cagliari, Italy
| | - Yi Sun
- Key Laboratory of Adolescent Health Assessment and Exercise Intervention of Ministry of Education, East China Normal University, Shanghai, China
- School of Physical Education & Health Care, East China Normal University, Shanghai, People's Republic of China
| | - L Bruce Gladden
- School of Kinesiology, Auburn University, Auburn, Alabama United States
| | - Nicola Lai
- Department of Mechanical, Chemical and Materials Engineering, University of Cagliari, Italy
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia United States
- Biomedical Engineering Institute, Old Dominion University, Norfolk, Virginia, United States
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Interaction of Factors Determining Critical Power. Sports Med 2023; 53:595-613. [PMID: 36622556 PMCID: PMC9935749 DOI: 10.1007/s40279-022-01805-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2022] [Indexed: 01/10/2023]
Abstract
The physiological determinants of high-intensity exercise tolerance are important for both elite human performance and morbidity, mortality and disease in clinical settings. The asymptote of the hyperbolic relation between external power and time to task failure, critical power, represents the threshold intensity above which systemic and intramuscular metabolic homeostasis can no longer be maintained. After ~ 60 years of research into the phenomenon of critical power, a clear understanding of its physiological determinants has emerged. The purpose of the present review is to critically examine this contemporary evidence in order to explain the physiological underpinnings of critical power. Evidence demonstrating that alterations in convective and diffusive oxygen delivery can impact upon critical power is first addressed. Subsequently, evidence is considered that shows that rates of muscle oxygen utilisation, inferred via the kinetics of pulmonary oxygen consumption, can influence critical power. The data reveal a clear picture that alterations in the rates of flux along every step of the oxygen transport and utilisation pathways influence critical power. It is also clear that critical power is influenced by motor unit recruitment patterns. On this basis, it is proposed that convective and diffusive oxygen delivery act in concert with muscle oxygen utilisation rates to determine the intracellular metabolic milieu and state of fatigue within the myocytes. This interacts with exercising muscle mass and motor unit recruitment patterns to ultimately determine critical power.
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Cheema U. Position Paper Progress in the development of biomimetic engineered human tissues. J Tissue Eng 2023; 14:20417314221145663. [PMID: 36874985 PMCID: PMC9974615 DOI: 10.1177/20417314221145663] [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: 06/21/2022] [Accepted: 11/28/2022] [Indexed: 03/07/2023] Open
Abstract
Tissue engineering (TE) is the multi-disciplinary approach to building 3D human tissue equivalents in the laboratory. The advancement of medical sciences and allied scientific disciplines have aspired to engineer human tissues for three decades. To date there is limited use of TE tissues/organs as replacement body parts in humans. This position paper outlines advances in engineering of specific tissues and organs with tissue-specific challenges. This paper outlines the technologies most successful for engineering tissues and key areas of advancement.
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Affiliation(s)
- Umber Cheema
- Division of Surgery and interventional science, UCL Centre for 3D models of Health and Disease, Fitzrovia
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Russell McEvoy GM, Wells BN, Kiley ME, Kaur KK, Fraser GM. Dynamics of capillary blood flow responses to acute local changes in oxygen and carbon dioxide concentrations. Front Physiol 2022; 13:1052449. [PMID: 36561216 PMCID: PMC9764012 DOI: 10.3389/fphys.2022.1052449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 11/15/2022] [Indexed: 12/24/2022] Open
Abstract
Objectives: We aimed to quantify the magnitude and time transients of capillary blood flow responses to acute changes in local oxygen concentration ([O2]), and carbon dioxide concentration ([CO2]) in skeletal muscle. Additionally, we sought to quantify the combined response to both low [O2] and high [CO2] to mimic muscle microenvironment changes at the onset of exercise. Methods: 13 Sprague Dawley rats were anaesthetized, mechanically ventilated, and instrumented with indwelling catheters for systemic monitoring. The extensor digitorum longus muscle was blunt dissected, and reflected over a microfluidic gas exchange chamber in the stage of an inverted microscope. Four O2 challenges, four CO2 challenges, and a combined low O2 (7-2%) and high CO2 (5-10%) challenges were delivered to the surface with simultaneous visualization of capillary blood flow responses. Recordings were made for each challenge over a 1-min baseline period followed by a 2-min step change. The combined challenge employed a 1-min [O2] challenge followed by a 2-min change in [CO2]. Mean data for each sequence were fit using least-squared non-linear exponential models to determine the dynamics of each response. Results: 7-2% [O2] challenges decreased capillary RBC saturation within 2 s following the step change (46.53 ± 19.56% vs. 48.51 ± 19.02%, p < 0.0001, τ = 1.44 s), increased RBC velocity within 3 s (228.53 ± 190.39 μm/s vs. 235.74 ± 193.52 μm/s, p < 0.0003, τ = 35.54 s) with a 52% peak increase by the end of the challenge, hematocrit and supply rate show similar dynamics. 5-10% [CO2] challenges increased RBC velocity within 2 s following the step change (273.40 ± 218.06 μm/s vs. 276.75 ± 215.94 μm/s, p = 0.007, τ = 79.34s), with a 58% peak increase by the end of the challenge, supply rate and hematocrit show similar dynamics. Combined [O2] and [CO2] challenges resulted in additive responses to all microvascular hemodynamic measures with a 103% peak velocity increase by the end of the collection period. Data for mean responses and exponential fitting parameters are reported for all challenges. Conclusion: Microvascular level changes in muscle [O2] and [CO2] provoked capillary hemodynamic responses with differing time transients. Simulating exercise via combined [O2] and [CO2] challenges demonstrated the independent and additive nature of local blood flow responses to these agents.
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Halvorson BD, Menon NJ, Goldman D, Frisbee SJ, Goodwill AG, Butcher JT, Stapleton PA, Brooks SD, d'Audiffret AC, Wiseman RW, Lombard JH, Brock RW, Olfert IM, Chantler PD, Frisbee JC. The development of peripheral microvasculopathy with chronic metabolic disease in obese Zucker rats: a retrograde emergence? Am J Physiol Heart Circ Physiol 2022; 323:H475-H489. [PMID: 35904886 PMCID: PMC9448278 DOI: 10.1152/ajpheart.00264.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/05/2022] [Accepted: 07/26/2022] [Indexed: 11/22/2022]
Abstract
The study of peripheral vasculopathy with chronic metabolic disease is challenged by divergent contributions from spatial (the level of resolution or specific tissue being studied) and temporal origins (evolution of the developing impairments in time). Over many years of studying the development of skeletal muscle vasculopathy and its functional implications, we may be at the point of presenting an integrated conceptual model that addresses these challenges within the obese Zucker rat (OZR) model. At the early stages of metabolic disease, where systemic markers of elevated cardiovascular disease risk are present, the only evidence of vascular dysfunction is at postcapillary and collecting venules, where leukocyte adhesion/rolling is elevated with impaired venular endothelial function. As metabolic disease severity and duration increases, reduced microvessel density becomes evident as well as increased variability in microvascular hematocrit. Subsequently, hemodynamic impairments to distal arteriolar networks emerge, manifesting as increasing perfusion heterogeneity and impaired arteriolar reactivity. This retrograde "wave of dysfunction" continues, creating a condition wherein deficiencies to the distal arteriolar, capillary, and venular microcirculation stabilize and impairments to proximal arteriolar reactivity, wall mechanics, and perfusion distribution evolve. This proximal arteriolar dysfunction parallels increasing failure in fatigue resistance, hyperemic responses, and O2 uptake within self-perfused skeletal muscle. Taken together, these results present a conceptual model for the retrograde development of peripheral vasculopathy with chronic metabolic disease and provide insight into the timing and targeting of interventional strategies to improve health outcomes.NEW & NOTEWORTHY Working from an established database spanning multiple scales and times, we studied progression of peripheral microvascular dysfunction in chronic metabolic disease. The data implicate the postcapillary venular endothelium as the initiating site for vasculopathy. Indicators of dysfunction, spanning network structures, hemodynamics, vascular reactivity, and perfusion progress in an insidious retrograde manner to present as functional impairments to muscle blood flow and performance much later. The silent vasculopathy progression may provide insight into clinical treatment challenges.
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Affiliation(s)
- Brayden D Halvorson
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Nithin J Menon
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Daniel Goldman
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Stephanie J Frisbee
- Department Pathology and Laboratory Medicine, University of Western Ontario, London, Ontario, Canada
| | - Adam G Goodwill
- Department of Integrative Medical Sciences, Northeastern Ohio Medical University, Rootstown, Ohio
| | - Joshua T Butcher
- Department of Physiological Sciences, Oklahoma State University, Stillwater, Oklahoma
| | - Phoebe A Stapleton
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, New Jersey
| | - Steven D Brooks
- Laboratory of Malaria and Vector Research, Physiology Unit, National Institute of Allergy and Infectious Diseases, Rockville, Maryland
| | | | - Robert W Wiseman
- Department of Physiology, Michigan State University, East Lansing, Michigan
- Department of Radiology, Michigan State University, East Lansing, Michigan
| | - Julian H Lombard
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Robert W Brock
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia
| | - I Mark Olfert
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia
- Division of Exercise Physiology, West Virginia University, Morgantown, West Virginia
| | - Paul D Chantler
- Division of Exercise Physiology, West Virginia University, Morgantown, West Virginia
| | - Jefferson C Frisbee
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
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12
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Afas KC, Goldman D. A two-layer continuously distributed capillary O 2 transport model applied to blood flow regulation in resting skeletal muscle. J Theor Biol 2022; 539:111058. [PMID: 35181287 DOI: 10.1016/j.jtbi.2022.111058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 02/07/2022] [Accepted: 02/08/2022] [Indexed: 10/19/2022]
Abstract
The microcirculation is the site of direct oxygen transfer from blood to tissue, and also of oxygen delivery control via regulation of local blood flow. In addition, a number of diseases including type II diabetes mellitus (DMII) and sepsis are known to produce microcirculatory dysfunction in their early phases. Given the complexity of microvascular structure and physiology, and the difficulty of measuring tissue oxygenation at the micro-scale, mathematical modelling has been necessary for understanding the physiology and pathophysiology of O2 transport in the microcirculation and for interpreting in vivo experiments. To advance this area, a model of blood-tissue O2 transport in skeletal muscle was recently developed which uses continuously distributed capillaries and includes O2 diffusion, convection, and consumption. The present work extends this model to two adjacent layers of skeletal muscle with different blood flow rates and applies it to study steady-state O2 transport when flow regulation is stimulated using an O2 exchange chamber. To generate a model which may be validated through in vivo experiments, an overlying O2 permeable membrane is included. The model is solved using traditional methods including separation of variables and Fourier decomposition, and to ensure smooth profiles at the muscle-muscle and muscle-membrane interfaces matching conditions are developed. The study presents qualitative verification for the model, using visualizations of tissue PO2 distributions for varying capillary density (CD), and presents capillary velocity response values in the near layer for varying chamber PO2 under the assumption that outlet capillary O2 saturation is equalized between adjacent layers. These compensatory velocity profiles, along with effective 'no-flux' chamber PO2 values, are presented for varying CD and tissue O2 consumption values. Insights gained from the two-layer model provide guidance for interpreting and planning future in-vivo experiments, and also provide motivation for further development of the model to improve understanding of the interaction between O2 transport and blood flow regulation.
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Affiliation(s)
- Keith Christian Afas
- School of Biomedical Engineering, University of Western Ontario, London, N6G1G8, Ontario, CA
| | - Daniel Goldman
- School of Biomedical Engineering, University of Western Ontario, London, N6G1G8, Ontario, CA; Department of Medical Biophysics, University of Western Ontario, London, N6A5C1, Ontario, CA; Department of Applied Mathematics, University of Western Ontario, London, N6A5C1, Ontario, CA.
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13
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Oxygen flux from capillary to mitochondria: integration of contemporary discoveries. Eur J Appl Physiol 2022; 122:7-28. [PMID: 34940908 PMCID: PMC8890444 DOI: 10.1007/s00421-021-04854-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 11/18/2021] [Indexed: 01/03/2023]
Abstract
Resting humans transport ~ 100 quintillion (1018) oxygen (O2) molecules every second to tissues for consumption. The final, short distance (< 50 µm) from capillary to the most distant mitochondria, in skeletal muscle where exercising O2 demands may increase 100-fold, challenges our understanding of O2 transport. To power cellular energetics O2 reaches its muscle mitochondrial target by dissociating from hemoglobin, crossing the red cell membrane, plasma, endothelial surface layer, endothelial cell, interstitial space, myocyte sarcolemma and a variable expanse of cytoplasm before traversing the mitochondrial outer/inner membranes and reacting with reduced cytochrome c and protons. This past century our understanding of O2's passage across the body's final O2 frontier has been completely revised. This review considers the latest structural and functional data, challenging the following entrenched notions: (1) That O2 moves freely across blood cell membranes. (2) The Krogh-Erlang model whereby O2 pressure decreases systematically from capillary to mitochondria. (3) Whether intramyocyte diffusion distances matter. (4) That mitochondria are separate organelles rather than coordinated and highly plastic syncytia. (5) The roles of free versus myoglobin-facilitated O2 diffusion. (6) That myocytes develop anoxic loci. These questions, and the intriguing notions that (1) cellular membranes, including interconnected mitochondrial membranes, act as low resistance conduits for O2, lipids and H+-electrochemical transport and (2) that myoglobin oxy/deoxygenation state controls mitochondrial oxidative function via nitric oxide, challenge established tenets of muscle metabolic control. These elements redefine muscle O2 transport models essential for the development of effective therapeutic countermeasures to pathological decrements in O2 supply and physical performance.
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14
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Effects of pulmonary hypertension on microcirculatory hemodynamics in rat skeletal muscle. Microvasc Res 2022; 141:104334. [PMID: 35104507 PMCID: PMC8928216 DOI: 10.1016/j.mvr.2022.104334] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 01/12/2022] [Accepted: 01/25/2022] [Indexed: 11/20/2022]
Abstract
Pulmonary hypertension (PH) has previously been characterized as a disease of the pulmonary vasculature that subsequently results in myocardial dysfunction. Heart failure compromises skeletal muscle microvascular function, which contributes to exercise intolerance. Therefore, we tested the hypothesis that such changes might be present in PH. Thus, we investigated skeletal muscle oxygen (O2) transport in the rat model of PH to determine if O2 delivery (Q̇O2) is impaired at the level of the microcirculation as evidenced via reduced red blood cell (RBC) flux, velocity, hematocrit, and percentage of capillaries flowing in quiescent muscle. Adult male Sprague-Dawley rats were randomized into healthy (n = 9) and PH groups (n = 9). Progressive PH was induced via a one-time intraperitoneal injection of monocrotaline (MCT; 50 mg/kg) and rats were monitored weekly via echocardiography. Intravital microscopy in the spinotrapezius muscle was performed when echocardiograms confirmed moderate PH (preceding right ventricular (RV) failure). At 25 ± 9 days post-MCT, PH rats displayed RV hypertrophy (RV/(Left ventricle + Septum): 0.28 ± 0.05 vs. 0.44 ± 0.11), pulmonary congestion, and increased right ventricular systolic pressure (21 ± 8 vs. 55 ± 14 mm Hg) compared to healthy rats (all P < 0.05). Reduced capillary RBC velocity (403 ± 140 vs. 227 ± 84 μm/s; P = 0.01), RBC flux (33 ± 12 vs. 23 ± 5 RBCs/s; P = 0.04) and % of capillaries supporting continuous RBC flux at rest (79 ± 8 vs. 56 ± 13%; P = 0.01) were evident in PH rats compared to healthy rats. When Q̇O2 within a given field of view was quantified (RBC flux x % of capillaries supporting continuous RBC flux), PH rats demonstrated lower overall Q̇O2 (↓ 50%; P = 0.002). These data support that microcirculatory hemodynamic impairments (↓ Q̇O2 and therefore altered Q̇O2-to-V̇O2 matching) may compromise blood-myocyte O2 transport in PH. The mechanistic bases for decreased capillary RBC flux, velocity, and percentage of capillaries supporting RBC flow remains an important topic.
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15
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Abstract
The design of the energy metabolism system in striated muscle remains a major area of investigation. Here, we review our current understanding and emerging hypotheses regarding the metabolic support of muscle contraction. Maintenance of ATP free energy, so called energy homeostasis, via mitochondrial oxidative phosphorylation is critical to sustained contractile activity, and this major design criterion is the focus of this review. Cell volume invested in mitochondria reduces the space available for generating contractile force, and this spatial balance between mitochondria acontractile elements to meet the varying sustained power demands across muscle types is another important design criterion. This is accomplished with remarkably similar mass-specific mitochondrial protein composition across muscle types, implying that it is the organization of mitochondria within the muscle cell that is critical to supporting sustained muscle function. Beyond the production of ATP, ubiquitous distribution of ATPases throughout the muscle requires rapid distribution of potential energy across these large cells. Distribution of potential energy has long been thought to occur primarily through facilitated metabolite diffusion, but recent analysis has questioned the importance of this process under normal physiological conditions. Recent structural and functional studies have supported the hypothesis that the mitochondrial reticulum provides a rapid energy distribution system via the conduction of the mitochondrial membrane potential to maintain metabolic homeostasis during contractile activity. We extensively review this aspect of the energy metabolism design contrasting it with metabolite diffusion models and how mitochondrial structure can play a role in the delivery of energy in the striated muscle.
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Affiliation(s)
- Brian Glancy
- Muscle Energetics Laboratory, National Heart, Lung, and Blood Insititute and National Institute of Arthritis and Musculoskeletal and Skin Disease, Bethesda, Maryland
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Insititute, Bethesda, Maryland
| | - Robert S Balaban
- Muscle Energetics Laboratory, National Heart, Lung, and Blood Insititute and National Institute of Arthritis and Musculoskeletal and Skin Disease, Bethesda, Maryland
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Insititute, Bethesda, Maryland
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16
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Lemieux P, Birot O. Altitude, Exercise, and Skeletal Muscle Angio-Adaptive Responses to Hypoxia: A Complex Story. Front Physiol 2021; 12:735557. [PMID: 34552509 PMCID: PMC8450406 DOI: 10.3389/fphys.2021.735557] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 08/16/2021] [Indexed: 12/18/2022] Open
Abstract
Hypoxia, defined as a reduced oxygen availability, can be observed in many tissues in response to various physiological and pathological conditions. As a hallmark of the altitude environment, ambient hypoxia results from a drop in the oxygen pressure in the atmosphere with elevation. A hypoxic stress can also occur at the cellular level when the oxygen supply through the local microcirculation cannot match the cells’ metabolic needs. This has been suggested in contracting skeletal myofibers during physical exercise. Regardless of its origin, ambient or exercise-induced, muscle hypoxia triggers complex angio-adaptive responses in the skeletal muscle tissue. These can result in the expression of a plethora of angio-adaptive molecules, ultimately leading to the growth, stabilization, or regression of muscle capillaries. This remarkable plasticity of the capillary network is referred to as angio-adaptation. It can alter the capillary-to-myofiber interface, which represent an important determinant of skeletal muscle function. These angio-adaptive molecules can also be released in the circulation as myokines to act on distant tissues. This review addresses the respective and combined potency of ambient hypoxia and exercise to generate a cellular hypoxic stress in skeletal muscle. The major skeletal muscle angio-adaptive responses to hypoxia so far described in this context will be discussed, including existing controversies in the field. Finally, this review will highlight the molecular complexity of the skeletal muscle angio-adaptive response to hypoxia and identify current gaps of knowledges in this field of exercise and environmental physiology.
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Affiliation(s)
- Pierre Lemieux
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University, Toronto, ON, Canada
| | - Olivier Birot
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University, Toronto, ON, Canada
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17
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Schulze KM, Weber RE, Colburn TD, Horn AG, Ade CJ, Hsu WW, Poole DC, Musch TI. The effects of pulmonary hypertension on skeletal muscle oxygen pressures in contracting rat spinotrapezius muscle. Exp Physiol 2021; 106:2070-2082. [PMID: 34469618 DOI: 10.1113/ep089631] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 08/26/2021] [Indexed: 01/02/2023]
Abstract
NEW FINDINGS What is the central question of this study? Does impairment in the dynamics of O2 transport in skeletal muscle during a series of contractions constitute a potential mechanism underlying reduced exercise capacity in pulmonary hypertension? What is the main finding and its importance? Pulmonary hypertension compromises the dynamic matching of skeletal muscle O2 delivery-to-utilization following contraction onset in the rat spinotrapezius muscle. These results implicate a role for vascular dysfunction in the slow V ̇ O 2 kinetics and exercise intolerance present in pulmonary hypertension. ABSTRACT Pulmonary hypertension (PH) is characterized by pulmonary vascular dysfunction and exercise intolerance due, in part, to compromised pulmonary and cardiac function. We tested the hypothesis that there are peripheral (i.e., skeletal muscle) aberrations in O2 delivery ( Q ̇ O 2 )-to-O2 utilization ( V ̇ O 2 ) matching and vascular control that might help to explain poor exercise tolerance in PH. Furthermore, we investigated the peripheral effects of nitric oxide (NO) in attenuating these decrements. Male Sprague-Dawley rats (n = 21) were administered monocrotaline (MCT; 50 mg/kg, i.p.) to induce PH. Disease progression was monitored via echocardiography. Phosphorescence quenching determined the O2 partial pressure in the interstitial space ( P O 2 is ) in the spinotrapezius muscle at rest and during contractions under control (SNP-) and NO-donor (sodium nitroprusside, SNP+) conditions. MCT rats displayed right ventricular (RV) hypertrophy (right ventricle/(left ventricle + septum): 0.44 (0.13) vs. 0.28 (0.05)), pulmonary congestion, increased RV systolic pressure (48 (18) vs. 20 (8) mmHg) and arterial hypoxaemia ( P a O 2 : 64 (9) vs. 82 (9) mmHg) compared to healthy controls (HC) (P < 0.05). P O 2 is was significantly lower in MCT rats during the first 30 s of SNP- contractions. SNP superfusion elevated P O 2 is in both groups; however, MCT rats demonstrated a lower P O 2 is throughout SNP+ contractions versus HC (P < 0.05). Thus, for small muscle mass exercise in MCT rats, muscle oxygenation is impaired across the rest-to-contractions transition and exogenous NO does not raise the Q ̇ O 2 -to- V ̇ O 2 ratio in contracting muscle to the same levels as HC. These data support muscle Q ̇ O 2 -to- V ̇ O 2 mismatch as a potential contributor to slow V ̇ O 2 kinetics and therefore exercise intolerance in PH and suggest peripheral vascular dysfunction or remodelling as a possible mechanism.
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Affiliation(s)
- Kiana M Schulze
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Ramona E Weber
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Andrew G Horn
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Carl J Ade
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Wei-Wen Hsu
- Department of Environmental and Public Health Sciences, University of Cincinnati, Cincinnati, OH, USA
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA.,Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, USA
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA.,Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, USA
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18
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Colburn TD, Weber RE, Schulze KM, Sue Hageman K, Horn AG, Behnke BJ, Poole DC, Musch TI. Sexual dimorphism in vascular ATP-sensitive K + channel function supporting interstitial PO2 via convective and/or diffusive O 2 transport. J Physiol 2021; 599:3279-3293. [PMID: 34101850 PMCID: PMC8451062 DOI: 10.1113/jp281120] [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: 11/17/2020] [Accepted: 04/14/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Inhibition of pancreatic ATP-sensitive K+ (KATP ) channels is the intended effect of oral sulphonylureas to increase insulin release in diabetes. However, pertinent to off-target effects of sulphonylurea medication, sex differences in cardiac KATP channel function exist, whereas potential sex differences in vascular KATP channel function remain unknown. In the present study, we assessed vascular KATP channel function (topical glibenclamide superfused onto fast-twitch oxidative skeletal muscle) supporting blood flow and interstitial O2 delivery-utilization matching ( P O 2 is) during twitch contractions in male, female during pro-oestrus and ovariectomized female (F+OVX) rats. Glibenclamide decreased blood flow (convective O2 transport) and interstitial P O 2 in male and female, but not F+OVX, rats. Compared to males, females also demonstrated impaired diffusive O2 transport and a faster fall in interstitial P O 2 . Our demonstration, in rats, that sex differences in vascular KATP channel function exist support the tentative hypothesis that oral sulphonylureas may exacerbate exercise intolerance and morbidity, especially in premenopausal females. ABSTRACT Vascular ATP-sensitive K+ (KATP ) channels support skeletal muscle blood flow ( Q ̇ m ), interstitial O2 delivery ( Q ̇ O 2 )-utilization ( V ̇ O 2 ) matching (i.e. interstitial-myocyte O2 flux driving pressure; P O 2 is) and exercise tolerance. Potential sex differences in skeletal muscle vascular KATP channel function remain largely unexplored. We hypothesized that local skeletal muscle KATP channel inhibition via glibenclamide superfusion (5 mg kg-1 GLI; sulphonylurea diabetes medication) in anaesthetized female Sprague-Dawley rats, compared to males, would demonstrate greater reductions in contracting (1 Hz, 7 V, 180 s) fast-twitch oxidative mixed gastrocnemius (97% type IIA+IID/X+IIB) Q ̇ m (15 μm microspheres) and P O 2 is (phosphorescence quenching), resulting from more compromised convective ( Q ̇ O 2 ) and diffusive ( D O 2 ) O2 conductances. Furthermore, these GLI-induced reductions in ovary-intact females measured during pro-oestrus would be diminished following ovariectomy (F+OVX). GLI similarly impaired mixed gastrocnemius V ̇ O 2 in both males (↓28%) and females (↓33%, both P < 0.032) via reduced Q ̇ m (male: ↓31%, female: ↓35%, both P < 0.020), Q ̇ O 2 (male: 5.6 ± 0.5 vs. 4.0 ± 0.5, female: 6.4 ± 1.1 vs. 4.2 ± 0.6 mL O2 min-1 100 g tissue-1 , P < 0.022) and the resulting P O 2 is, with females also demonstrating a reduced D O 2 (0.40 ± 0.07 vs. 0.30 ± 0.04 mL O2 min-1 100 g tissue-1 , P < 0.042) and a greater GLI-induced speeding of P O 2 is fall (mean response time: Sex × Drug interaction, P = 0.026). Conversely, GLI did not impair the mixed gastrocnemius of F+OVX rats. Therefore, in patients taking sulphonylureas, these results support the potential for impaired vascular KATP channel function to compromise muscle Q ̇ m and therefore exercise tolerance. Such an effect, if present, would likely contribute to adverse cardiovascular events in premenopausal females more than males.
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Affiliation(s)
- Trenton D. Colburn
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Ramona E. Weber
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Kiana M. Schulze
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - K. Sue Hageman
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Andrew G. Horn
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Brad J. Behnke
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - David C. Poole
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Timothy I. Musch
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
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19
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Jones AM, Vanhatalo A, Seals DR, Rossman MJ, Piknova B, Jonvik KL. Dietary Nitrate and Nitric Oxide Metabolism: Mouth, Circulation, Skeletal Muscle, and Exercise Performance. Med Sci Sports Exerc 2021; 53:280-294. [PMID: 32735111 DOI: 10.1249/mss.0000000000002470] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Nitric oxide (NO) is a gaseous signaling molecule that plays an important role in myriad physiological processes, including the regulation of vascular tone, neurotransmission, mitochondrial respiration, and skeletal muscle contractile function. NO may be produced via the canonical NO synthase-catalyzed oxidation of l-arginine and also by the sequential reduction of nitrate to nitrite and then NO. The body's nitrate stores can be augmented by the ingestion of nitrate-rich foods (primarily green leafy vegetables). NO bioavailability is greatly enhanced by the activity of bacteria residing in the mouth, which reduce nitrate to nitrite, thereby increasing the concentration of circulating nitrite, which can be reduced further to NO in regions of low oxygen availability. Recent investigations have focused on promoting this nitrate-nitrite-NO pathway to positively affect indices of cardiovascular health and exercise tolerance. It has been reported that dietary nitrate supplementation with beetroot juice lowers blood pressure in hypertensive patients, and sodium nitrite supplementation improves vascular endothelial function and reduces the stiffening of large elastic arteries in older humans. Nitrate supplementation has also been shown to enhance skeletal muscle function and to improve exercise performance in some circumstances. Recently, it has been established that nitrate concentration in skeletal muscle is much higher than that in blood and that muscle nitrate stores are exquisitely sensitive to dietary nitrate supplementation and deprivation. In this review, we consider the possibility that nitrate represents an essential storage form of NO and discuss the integrated function of the oral microbiome, circulation, and skeletal muscle in nitrate-nitrite-NO metabolism, as well as the practical relevance for health and performance.
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Affiliation(s)
- Andrew M Jones
- Department of Sport and Health Sciences, University of Exeter, Exeter, UNITED KINGDOM
| | - Anni Vanhatalo
- Department of Sport and Health Sciences, University of Exeter, Exeter, UNITED KINGDOM
| | - Douglas R Seals
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO
| | - Matthew J Rossman
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO
| | - Barbora Piknova
- Molecular Medicine Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
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20
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Poole DC, Behnke BJ, Musch TI. The role of vascular function on exercise capacity in health and disease. J Physiol 2021; 599:889-910. [PMID: 31977068 PMCID: PMC7874303 DOI: 10.1113/jp278931] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 12/10/2019] [Indexed: 12/16/2022] Open
Abstract
Three sentinel parameters of aerobic performance are the maximal oxygen uptake ( V ̇ O 2 max ), critical power (CP) and speed of the V ̇ O 2 kinetics following exercise onset. Of these, the latter is, perhaps, the cardinal test of integrated function along the O2 transport pathway from lungs to skeletal muscle mitochondria. Fast V ̇ O 2 kinetics demands that the cardiovascular system distributes exercise-induced blood flow elevations among and within those vascular beds subserving the contracting muscle(s). Ideally, this process must occur at least as rapidly as mitochondrial metabolism elevates V ̇ O 2 . Chronic disease and ageing create an O2 delivery (i.e. blood flow × arterial [O2 ], Q ̇ O 2 ) dependency that slows V ̇ O 2 kinetics, decreasing CP and V ̇ O 2 max , increasing the O2 deficit and sowing the seeds of exercise intolerance. Exercise training, in contrast, does the opposite. Within the context of these three parameters (see Graphical Abstract), this brief review examines the training-induced plasticity of key elements in the O2 transport pathway. It asks how structural and functional vascular adaptations accelerate and redistribute muscle Q ̇ O 2 and thus defend microvascular O2 partial pressures and capillary blood-myocyte O2 diffusion across a ∼100-fold range of muscle V ̇ O 2 values. Recent discoveries, especially in the muscle microcirculation and Q ̇ O 2 -to- V ̇ O 2 heterogeneity, are integrated with the O2 transport pathway to appreciate how local and systemic vascular control helps defend V ̇ O 2 kinetics and determine CP and V ̇ O 2 max in health and how vascular dysfunction in disease predicates exercise intolerance. Finally, the latest evidence that nitrate supplementation improves vascular and therefore aerobic function in health and disease is presented.
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Affiliation(s)
- David C Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Brad J Behnke
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Timothy I Musch
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
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21
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Golub AS, Nugent WH, Song BK. Spike of interstitial PO 2 produced by a twitch in rhythmically contracted muscle. Physiol Rep 2021; 9:e14699. [PMID: 33400848 PMCID: PMC7785101 DOI: 10.14814/phy2.14699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/27/2020] [Accepted: 12/05/2020] [Indexed: 11/29/2022] Open
Abstract
Oxygen (O2 ) exchange between capillaries and muscle cells in exercising muscles is of great interest for physiology and kinesiology. However, methodical limitations prevent O2 measurements on the millisecond scale. To bypass the constraints of quasi-continuous recording, progressive measurements of O2 partial pressure (PO2 ) in rhythmically contracting skeletal muscle were compiled to describe the O2 kinetics surrounding and including a single muscle contraction. Phosphorescence quenching microscopy measured PO2 in the interstitium of the rat spinotrapezius muscle. Measurements were triggered by contraction-inducing electrical pulses. For the first 60 seconds, measurement preceeded stimulation. After 60, measurement followed with a progressive 20 ms increment. Thus, the first 60 measurements describe the overall PO2 response to electrical stimulation initiated after a 10 second rest period, while 61-100 (stroboscopic mode) were compiled into a single 800 ms profile of the PO2 transient surrounding muscle contraction. Thirty seconds of stimulated contractions decreased interstitial PO2 from a baseline of 71 ± 1.4 mmHg to an "active" steady-state of 43 ± 1.5 mmHg. The stroboscopic mode compilation revealed an unexpected post-contractile rise in PO2 as a 205 ms spike with a maximum amplitude of 58 ± 3.8 mmHg at 68 ms, which restored 58% of the PO2 drop from baseline. Interpretation of this phenomenon is based on classical experiments by G.V. Anrep (1935), who discovered the rapid thrust of blood flow associated with muscle contraction. In addition to the metabolic implications during exercise, the physiological impact of these PO2 spikes may grow with an increased rate of rhythmical contractions in muscle or heart. NEW&NOTEWORTHY: The principal finding is a spike of interstitial PO2 , produced by a twitch in a rhythmically contracting muscle. A possible mechanism is flushing capillaries with arterial blood by mechanical forces. A technical novelty is the PO2 measurement with a "stroboscopic mode" and progressively increasing delay between stimulator pulse and PO2 measuring. That permitted a 20 ms time resolution for a 205 ms spike duration, using an excitation flash rate one per second.
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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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23
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Colburn TD, Weber RE, Hageman KS, Caldwell JT, Schulze KM, Ade CJ, Behnke BJ, Poole DC, Musch TI. Vascular ATP-sensitive K + channels support maximal aerobic capacity and critical speed via convective and diffusive O 2 transport. J Physiol 2020; 598:4843-4858. [PMID: 32798233 PMCID: PMC7874302 DOI: 10.1113/jp280232] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 08/13/2020] [Indexed: 12/26/2022] Open
Abstract
KEY POINTS Oral sulphonylureas, widely prescribed for diabetes, inhibit pancreatic ATP-sensitive K+ (KATP ) channels to increase insulin release. However, KATP channels are also located within vascular (endothelium and smooth muscle) and muscle (cardiac and skeletal) tissue. We evaluated left ventricular function at rest, maximal aerobic capacity ( V ̇ O2 max) and submaximal exercise tolerance (i.e. speed-duration relationship) during treadmill running in rats, before and after systemic KATP channel inhibition via glibenclamide. Glibenclamide impaired critical speed proportionally more than V ̇ O2 max but did not alter resting cardiac output. Vascular KATP channel function (topical glibenclamide superfused onto hindlimb skeletal muscle) resolved a decreased blood flow and interstitial PO2 during twitch contractions reflecting impaired O2 delivery-to-utilization matching. Our findings demonstrate that systemic KATP channel inhibition reduces V ̇ O2 max and critical speed during treadmill running in rats due, in part, to impaired convective and diffusive O2 delivery, and thus V ̇ O2 , especially within fast-twitch oxidative skeletal muscle. ABSTRACT Vascular ATP-sensitive K+ (KATP ) channels support skeletal muscle blood flow and microvascular oxygen delivery-to-utilization matching during exercise. However, oral sulphonylurea treatment for diabetes inhibits pancreatic KATP channels to enhance insulin release. Herein we tested the hypotheses that: i) systemic KATP channel inhibition via glibenclamide (GLI; 10 mg kg-1 i.p.) would decrease cardiac output at rest (echocardiography), maximal aerobic capacity ( V ̇ O2 max) and the speed-duration relationship (i.e. lower critical speed (CS)) during treadmill running; and ii) local KATP channel inhibition (5 mg kg-1 GLI superfusion) would decrease blood flow (15 µm microspheres), interstitial space oxygen pressures (PO2 is; phosphorescence quenching) and convective and diffusive O2 transport ( Q ̇ O2 and DO2 , respectively; Fick Principle and Law of Diffusion) in contracting fast-twitch oxidative mixed gastrocnemius muscle (MG: 9% type I+IIa fibres). At rest, GLI slowed left ventricular relaxation (2.11 ± 0.59 vs. 1.70 ± 0.23 cm s-1 ) and decreased heart rate (321 ± 23 vs. 304 ± 22 bpm, both P < 0.05) while cardiac output remained unaltered (219 ± 64 vs. 197 ± 39 ml min-1 , P > 0.05). During exercise, GLI reduced V ̇ O2 max (71.5 ± 3.1 vs. 67.9 ± 4.8 ml kg-1 min-1 ) and CS (35.9 ± 2.4 vs. 31.9 ± 3.1 m min-1 , both P < 0.05). Local KATP channel inhibition decreased MG blood flow (52 ± 25 vs. 34 ± 13 ml min-1 100 g tissue-1 ) and PO2 isnadir (5.9 ± 0.9 vs. 4.7 ± 1.1 mmHg) during twitch contractions. Furthermore, MG V ̇ O2 was reduced via impaired Q ̇ O2 and DO2 (P < 0.05 for each). Collectively, these data support that vascular KATP channels help sustain submaximal exercise tolerance in healthy rats. For patients taking sulfonylureas, KATP channel inhibition may exacerbate exercise intolerance.
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Affiliation(s)
- Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Ramona E Weber
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - K Sue Hageman
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Jacob T Caldwell
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Kiana M Schulze
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Carl J Ade
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Brad J Behnke
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
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24
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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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25
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Goulding RP, Okushima D, Marwood S, Poole DC, Barstow TJ, Lei TH, Kondo N, Koga S. Impact of supine exercise on muscle deoxygenation kinetics heterogeneity: mechanistic insights into slow pulmonary oxygen uptake dynamics. J Appl Physiol (1985) 2020; 129:535-546. [PMID: 32702271 DOI: 10.1152/japplphysiol.00213.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Oxygen uptake (V̇o2) kinetics are slowed in the supine (S) position purportedly due to impaired muscle O2 delivery ([Formula: see text]); however, these conclusions are predicated on single-site measurements in superficial muscle using continuous-wave near-infrared spectroscopy (NIRS). This study aimed to determine the impact of body position [i.e., upright (U) versus S] on deep and superficial muscle deoxygenation (deoxy[heme]) using time-resolved (TR-) NIRS, and how these relate to slowed pulmonary V̇o2 kinetics. Seventeen healthy men completed constant power tests during 1) S heavy-intensity exercise and 2) U exercise at the same absolute work rate, with a subset of 10 completing additional tests at the same relative work rate as S. Pulmonary V̇o2 was measured breath-by-breath and, deoxy- and total[heme] were resolved via TR-NIRS in the superficial and deep vastus lateralis and superficial rectus femoris. The fundamental phase V̇o2 time constant was increased during S compared with U (S: 36 ± 10 vs. U: 27 ± 8 s; P < 0.001). The deoxy[heme] amplitude (S: 25-28 vs. U: 13-18 µM; P < 0.05) and total[heme] amplitude (S: 17-20 vs. U: 9-16 µM; P < 0.05) were greater in S compared with U and were consistent for the same absolute (above data) and relative work rates (n = 10, all P < 0.05). The greater deoxy- and total[heme] amplitudes in S vs. U supports that reduced perfusive [Formula: see text] in S, even within deep muscle, necessitated a greater reliance on fractional O2 extraction and diffusive [Formula: see text]. The slower V̇o2 kinetics in S versus U demonstrates that, ultimately, these adjustments were insufficient to prevent impairments in whole body oxidative metabolism.NEW & NOTEWORTHY We show that supine exercise causes a greater degree of muscle deoxygenation in both deep and superficial muscle and increases the spatial heterogeneity of muscle deoxygenation. Therefore, this study suggests that any O2 delivery gradient toward deep versus superficial muscle is insufficient to mitigate impairments in oxidative function in response to reduced whole muscle O2 delivery. More heterogeneous muscle deoxygenation is associated with slower V̇o2 kinetics.
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Affiliation(s)
- Richie P Goulding
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan.,International Research Fellow of Japan Society for Promotion of Sciences, Tokyo, Japan
| | - Dai Okushima
- Osaka International University, Moriguchi, Japan
| | - Simon Marwood
- School of Health Sciences, Liverpool Hope University, Liverpool, Merseyside, United Kingdom
| | - 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
| | - Tze-Huan Lei
- International Research Fellow of Japan Society for Promotion of Sciences, Tokyo, Japan.,Applied Physiology Laboratory, Kobe University, Kobe, Japan
| | - Narihiko Kondo
- Applied Physiology Laboratory, Kobe University, Kobe, Japan
| | - Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
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26
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Tabuchi A, Craig JC, Hirai DM, Colburn TD, Kano Y, Poole DC, Musch TI. Systemic NOS inhibition reduces contracting muscle oxygenation more in intact female than male rats. Nitric Oxide 2020; 100-101:38-44. [PMID: 32371102 DOI: 10.1016/j.niox.2020.04.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/14/2020] [Accepted: 04/22/2020] [Indexed: 10/24/2022]
Abstract
Females respond to baroreceptor stimulation with enhanced modulation of heart rate (HR) to regulate blood pressure and also express greater reliance on nitric oxide (NO) for vascular control compared to males. Sex differences in muscle oxygenation consequent to central hemodynamic challenge induced by systemic NO synthase (NOS) inhibition are unknown. We tested the hypotheses that systemic NOS inhibition would induce lower contracting skeletal muscle oxygenation in females compared to males. The spinotrapezius of Sprague-Dawley rats (females (♀) = 9, males (♂) = 9) was surgically exposed and contracted by electrical stimulation (180s, 1 Hz, ~6 V) under pentobarbital sodium anesthesia. Oxyphor G4 was injected into the muscle and phosphorescence quenching was used to measure the interstitial PO2 (PO2is, determined by O2 delivery-to-utilization matching) under control (Krebs-Henseleit solution) and after intra-arterial infusion of nitro-l-arginine methyl ester (l-NAME; NOS blockade; 10 mg kg-1). At rest, females showed a greater PO2is increase (ΔPO2is/ΔMAP) and HR (ΔHR/ΔMAP) reduction than males in response to the elevated MAP induced by systemic NOS inhibition (both p < 0.05). Following l-NAME, during the contracting steady-state, females exhibited lower PO2is than males (♂: 17.1 ± 1.4 vs ♀: 10.8 ± 1.4 mmHg, p < 0.05). The rate pressure product was lower in females than males (♂: 482 ± 14 vs ♀: 392 ± 29, p < 0.05) and correlated with the steady-state PO2is (r = 0.66, p < 0.05). These results support that females express greater reductions in HR than males in response to l-NAME-induced elevation of MAP via the baroreceptor reflex and provide new insights on how central hemodynamics affect skeletal muscle oxygenation in a sex-specific manner.
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Affiliation(s)
- Ayaka Tabuchi
- Departments of Kinesiology and Anatomy & Physiology, Kansas State University, Manhattan, KS, USA; Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Tokyo, Japan
| | - Jesse C Craig
- Departments of Kinesiology and Anatomy & Physiology, Kansas State University, Manhattan, KS, USA
| | - Daniel M Hirai
- Departments of Kinesiology and Anatomy & Physiology, Kansas State University, Manhattan, KS, USA
| | - Trenton D Colburn
- Departments of Kinesiology and Anatomy & Physiology, Kansas State University, Manhattan, KS, USA
| | - Yutaka Kano
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Tokyo, Japan
| | - David C Poole
- Departments of Kinesiology and Anatomy & Physiology, Kansas State University, Manhattan, KS, USA
| | - Timothy I Musch
- Departments of Kinesiology and Anatomy & Physiology, Kansas State University, Manhattan, KS, USA.
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27
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Colburn TD, Hirai DM, Craig JC, Ferguson SK, Weber RE, Schulze KM, Behnke BJ, Musch TI, Poole DC. Transcapillary PO 2 gradients in contracting muscles across the fibre type and oxidative continuum. J Physiol 2020; 598:3187-3202. [PMID: 32445225 DOI: 10.1113/jp279608] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 05/14/2020] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Within skeletal muscle the greatest resistance to oxygen transport is thought to reside across the short distance at the red blood cell-myocyte interface. These structures generate a significant transmural oxygen pressure (PO2 ) gradient in mixed fibre-type muscle. Increasing O2 flux across the capillary wall during exercise depends on: (i) the transmural O2 pressure gradient, which is maintained in mixed-fibre muscle, and/or (ii) elevating diffusing properties between microvascular and interstitial compartments resulting, in part, from microvascular haemodynamics and red blood cell distribution. We evaluated the PO2 within the microvascular and interstitial spaces of muscles spanning the slow- to fast-twitch fibre and high- to low-oxidative capacity spectrums, at rest and during contractions, to assess the magnitude of transcapillary PO2 gradients in rats. Our findings demonstrate that, across the metabolic rest-contraction transition, the transcapillary pressure gradient for O2 flux is: (i) maintained in all muscle types, and (ii) the lowest in contracting highly oxidative fast-twitch muscle. ABSTRACT In mixed fibre-type skeletal muscle transcapillary PO2 gradients (PO2 mv-PO2 is; microvascular and interstitial, respectively) drive O2 flux across the blood-myocyte interface where the greatest resistance to that O2 flux resides. We assessed a broad spectrum of fibre-type and oxidative-capacity rat muscles across the rest-to-contraction (1 Hz, 120 s) transient to test the novel hypotheses that: (i) slow-twitch PO2 is would be greater than fast-twitch, (ii) muscles with greater oxidative capacity have greater PO2 is than glycolytic counterparts, and (iii) whether PO2 mv-PO2 is at rest is maintained during contractions across all muscle types. PO2 mv and PO2 is were determined via phosphorescence quenching in soleus (SOL; 91% type I+IIa fibres and CSa: ∼21 μmol min-1 g-1 ), peroneal (PER; 33% and ∼20 μmol min-1 g-1 ), mixed (MG; 9% and ∼26 μmol min-1 g-1 ) and white gastrocnemius (WG; 0% and ∼8 μmol min-1 g-1 ) across the rest-contraction transient. PO2 mv was higher than PO2 is in each muscle (∼6-13 mmHg; P < 0.05). SOL PO2 isarea was greater than in the fast-twitch muscles during contractions (P < 0.05). Oxidative muscles had greater PO2 isnadir (9.4 ± 0.8, 7.4 ± 0.9 and 6.4 ± 0.4; SOL, PER and MG, respectively) than WG (3.0 ± 0.3 mmHg, P < 0.05). The magnitude of PO2 mv-PO2 is at rest decreased during contractions in MG only (∼11 to 7 mmHg; time × (PO2 mv-PO2 is) interaction, P < 0.05). These data support the hypothesis that, since transcapillary PO2 gradients during contractions are maintained in all muscle types, increased O2 flux must occur via enhanced intracapillary diffusing conductance, which is most extreme in highly oxidative fast-twitch muscle.
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Affiliation(s)
| | - Daniel M Hirai
- Department of Health and Kinesiology, Purdue University, West Lafayette, IN
| | - Jesse C Craig
- Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Scott K Ferguson
- Department of Kinesiology and Exercise Sciences, University of Hawaii, Hilo, HI
| | - Ramona E Weber
- Department of Kinesiology, Kansas State University Manhattan, KS
| | - Kiana M Schulze
- Department of Kinesiology, Kansas State University Manhattan, KS
| | - Brad J Behnke
- Department of Kinesiology, Kansas State University Manhattan, KS
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University Manhattan, KS.,Department of Anatomy and Physiology, Kansas State University Manhattan, KS
| | - David C Poole
- Department of Kinesiology, Kansas State University Manhattan, KS.,Department of Anatomy and Physiology, Kansas State University Manhattan, KS
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28
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Okushima D, Poole DC, Barstow TJ, Kondo N, Chin LMK, Koga S. Effect of differential muscle activation patterns on muscle deoxygenation and microvascular haemoglobin regulation. Exp Physiol 2020; 105:531-541. [PMID: 31944446 PMCID: PMC10466155 DOI: 10.1113/ep088322] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 01/14/2020] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does the presence and extent of heterogeneity in the ratio of O2 delivery to uptake across human muscles relate specifically to different muscle activation patterns? What is the main finding and its importance? During ramp incremental knee-extension and cycling exercise, the profiles of muscle deoxygenation (deoxy[haemoglobin + myoglobin]) and diffusive O2 potential (total[haemoglobin + myoglobin]) in the vastus lateralis corresponded to different muscle activation strategies. However, this was not the case for the rectus femoris, where muscle activation and deoxygenation profiles were dissociated and might therefore be determined by other structural and/or functional attributes (e.g. arteriolar vascular regulation and control of red blood cell flux). ABSTRACT Near-infrared spectroscopy has revealed considerable heterogeneity in the ratio of O2 delivery to uptake as identified by disparate deoxygenation {deoxy[haemoglobin + myoglobin] (deoxy[Hb + Mb])} values in the exercising quadriceps. However, whether this represents a recruitment phenomenon or contrasting vascular and metabolic control, as seen among fibre types, has not been established. We used knee-extension (KE) and cycling (CE) incremental exercise protocols to examine whether differential muscle activation profiles could account for the heterogeneity of deoxy[Hb + Mb] and microvascular haemoconcentration (i.e. total[Hb + Mb]). Using time-resolved near-infrared spectroscopy for the quadriceps femoris (vastus lateralis and rectus femoris) during exhaustive ramp exercise in eight participants, we tested the following hypotheses: (i) the deoxy[Hb + Mb] (i.e. fractional O2 extraction) would relate to muscle activation levels across exercise protocols; and (ii) KE would induce greater total[Hb + Mb] (i.e. diffusive O2 potential) at task failure (i.e. peak O2 uptake) than CE irrespective of muscle site. At a given level of muscle activation, as assessed by the relative integrated EMG normalized to maximal voluntary contraction (%iEMGmax ), the vastus lateralis deoxy[Hb + Mb] profile was not different between exercise protocols. However, at peak O2 uptake and until 20% iEMGmax for CE, rectus femoris exhibited a lower deoxy[Hb + Mb] (83.2 ± 15.5 versus 98.2 ± 19.4 μm) for KE than for CE (P < 0.05). The total[Hb + Mb] at peak O2 uptake was not different between exercise protocols for either muscle site. These data support the hypothesis that the contrasting patterns of convective and diffusive O2 transport correspond to different muscle activation patterns in vastus lateralis but not rectus femoris. Thus, the differential deoxygenation profiles for rectus femoris across exercise protocols might be dependent upon specific facets of muscle architecture and functional haemodynamic events.
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Affiliation(s)
- Dai Okushima
- Applied Physiology Laboratory, Kobe Design University, Kobe, Hyogo, Japan
- Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
- Osaka International University, Moriguchi, Japan
| | - David C. Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Thomas J. Barstow
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | | | - Lisa M. K. Chin
- Rehabilitation Medicine Department, National Institutes of Health Clinical Center, Bethesda, Maryland
| | - Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Hyogo, Japan
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29
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Blottner D, Hastermann M, Weber R, Lenz R, Gambara G, Limper U, Rittweger J, Bosutti A, Degens H, Salanova M. Reactive Jumps Preserve Skeletal Muscle Structure, Phenotype, and Myofiber Oxidative Capacity in Bed Rest. Front Physiol 2020; 10:1527. [PMID: 32009969 PMCID: PMC6974579 DOI: 10.3389/fphys.2019.01527] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 12/04/2019] [Indexed: 12/18/2022] Open
Abstract
Identification of countermeasures able to prevent disuse-induced muscle wasting is crucial to increase performance of crew members during space flight as well as ameliorate patient’s clinical outcome after long immobilization periods. We report on the outcome of short but high-impact reactive jumps (JUMP) as countermeasure during 60 days of 6° head-down tilt (HDT) bed rest on myofiber size, type composition, capillarization, and oxidative capacity in tissue biopsies (pre/post/recovery) from the knee extensor vastus lateralis (VL) and deep calf soleus (SOL) muscle of 22 healthy male participants (Reactive jumps in a sledge, RSL-study 2015–2016, DLR:envihab, Cologne). Bed rest induced a slow-to-fast myofiber shift (type I –>II) with an increased prevalence of hybrid fibers in SOL after bed rest without jumps (control, CTRL, p = 0.016). In SOL, JUMP countermeasure in bed rest prevented both fast and slow myofiber cross-sectional area (CSA) decrements (p = 0.005) in CTRL group. In VL, bed rest only induced capillary rarefaction, as reflected by the decrease in local capillary-to-fiber ratio (LCFR) for both type II (pre vs. post/R + 10, p = 0.028/0.028) and type I myofibers (pre vs. R + 10, p = 0.012), which was not seen in the JUMP group. VO2maxFiber (pL × mm–1 × min–1) calculated from succinate dehydrogenase (SDH)-stained cryosections (OD660 nm) showed no significant differences between groups. High-impact jump training in bed rest did not prevent disuse-induced myofiber atrophy in VL, mitigated phenotype transition (type I – >II) in SOL, and attenuated capillary rarefaction in the prime knee extensor VL however with little impact on oxidative capacity changes.
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Affiliation(s)
- Dieter Blottner
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Institute of Integrative Neuroanatomy, Berlin, Germany.,NeuroMuscular Group, Center of Space Medicine and Extreme Environments, Berlin, Germany
| | - Maria Hastermann
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Institute of Integrative Neuroanatomy, Berlin, Germany.,NeuroMuscular Group, Center of Space Medicine and Extreme Environments, Berlin, Germany
| | - Robert Weber
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Institute of Integrative Neuroanatomy, Berlin, Germany
| | - Regina Lenz
- Department of Movement and Neurosciences, German Sports University, Cologne, Germany
| | - Guido Gambara
- Charité Comprehensive Cancer Center, Berlin, Germany.,German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Ulrich Limper
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany.,Department of Anesthesiology and Intensive Care Medicine, Merheim Medical Center, Hospitals of Cologne, University of Witten/Herdecke, Cologne, Germany
| | - Jörn Rittweger
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | | | - Hans Degens
- Research Centre for Musculoskeletal Science & Sports Medicine, Manchester Metropolitan University, Manchester, United Kingdom.,Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - Michele Salanova
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Institute of Integrative Neuroanatomy, Berlin, Germany.,NeuroMuscular Group, Center of Space Medicine and Extreme Environments, Berlin, Germany
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30
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Bailey SJ, Gandra PG, Jones AM, Hogan MC, Nogueira L. Incubation with sodium nitrite attenuates fatigue development in intact single mouse fibres at physiological P O 2 . J Physiol 2019; 597:5429-5443. [PMID: 31541562 DOI: 10.1113/jp278494] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 09/20/2019] [Indexed: 12/22/2022] Open
Abstract
KEY POINTS Dietary nitrate supplementation increases plasma nitrite concentration, which provides an oxygen-independent source of nitric oxide and can delay skeletal muscle fatigue. Nitrate supplementation has been shown to increase myofibre calcium release and force production in mouse skeletal muscle during contractions at a supra-physiological oxygen tension, but it is unclear whether nitrite exposure can delay fatigue development and improve myofibre calcium handling at a near-physiological oxygen tension. Single mouse muscle fibres acutely treated with nitrite had a lower force and cytosolic calcium concentration during single non-fatiguing contractions at a near-physiological oxygen tension. Nitrite treatment delayed fatigue development during repeated fatiguing isometric contractions at near-physiological, but not at supra-physiological, oxygen tension in combination with better maintenance of myofilament calcium sensitivity and sarcoplasmic reticulum calcium pumping. These findings improve understanding of the mechanisms by which increased skeletal muscle nitrite exposure might be ergogenic and imply that this is related to improved calcium handling. ABSTRACT Dietary nitrate (NO3 - ) supplementation, which increases plasma nitrite (NO2 - ) concentration, has been reported to attenuate skeletal muscle fatigue development. Sarcoplasmic reticulum (SR) calcium (Ca2+ ) release is enhanced in isolated single skeletal muscle fibres following NO3 - supplementation or NO2 - incubation at a supra-physiological P O 2 but it is unclear whether NO2 - incubation can alter Ca2+ handling and fatigue development at a near-physiological P O 2 . We hypothesised that NO2 - treatment would improve Ca2+ handling and delay fatigue at a physiological P O 2 in intact single mouse skeletal muscle fibres. Each muscle fibre was perfused with Tyrode solution pre-equilibrated with either 20% ( P O 2 ∼150 Torr) or 2% O2 ( P O 2 = 15.6 Torr) in the absence and presence of 100 µM NaNO2 . At supra-physiological P O 2 (i.e. 20% O2 ), time to fatigue was lowered by 34% with NaNO2 (control: 257 ± 94 vs. NaNO2 : 159 ± 46 s, Cohen's d = 1.63, P < 0.05), but extended by 21% with NaNO2 at 2% O2 (control: 308 ± 217 vs. NaNO2 : 368 ± 242 s, d = 1.14, P < 0.01). During the fatiguing contraction protocol completed with NaNO2 at 2% O2 , peak cytosolic Ca2+ concentration ([Ca2+ ]c ) was not different (P > 0.05) but [Ca2+ ]c accumulation between contractions was lower, concomitant with a greater SR Ca2+ pumping rate (P < 0.05) compared to the control condition. These results demonstrate that increased exposure to NO2 - blunts fatigue development at near-physiological, but not at supra-physiological, P O 2 through enhancing SR Ca2+ pumping rate in single skeletal muscle fibres. These findings extend our understanding of the mechanisms by which increased NO2 - exposure can mitigate skeletal muscle fatigue development.
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Affiliation(s)
- Stephen J Bailey
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.,School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Paulo G Gandra
- Section of Physiology; Division of Pulmonary, Critical Care & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA.,Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas (Unicamp), Campinas, Brazil
| | - Andrew M Jones
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Michael C Hogan
- Section of Physiology; Division of Pulmonary, Critical Care & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
| | - Leonardo Nogueira
- Section of Physiology; Division of Pulmonary, Critical Care & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA.,Instituto de Bioquímica Médica Leopoldo de Meis (Medical Biochemistry Institute Leopoldo de Meis), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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31
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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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32
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Craig JC, Colburn TD, Caldwell JT, Hirai DM, Tabuchi A, Baumfalk DR, Behnke BJ, Ade CJ, Musch TI, Poole DC. Central and peripheral factors mechanistically linked to exercise intolerance in heart failure with reduced ejection fraction. Am J Physiol Heart Circ Physiol 2019; 317:H434-H444. [PMID: 31225988 DOI: 10.1152/ajpheart.00164.2019] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Exercise intolerance is a primary symptom of heart failure (HF); however, the specific contribution of central and peripheral factors to this intolerance is not well described. The hyperbolic relationship between exercise intensity and time to exhaustion (speed-duration relationship) defines exercise tolerance but is underused in HF. We tested the hypotheses that critical speed (CS) would be reduced in HF, resting central functional measurements would correlate with CS, and the greatest HF-induced peripheral dysfunction would occur in more oxidative muscle. Multiple treadmill-constant speed runs to exhaustion were used to quantify CS and D' (distance coverable above CS) in healthy control (Con) and HF rats. Central function was determined via left ventricular (LV) Doppler echocardiography [fractional shortening (FS)] and a micromanometer-tipped catheter [LV end-diastolic pressure (LVEDP)]. Peripheral O2 delivery-to-utilization matching was determined via phosphorescence quenching (interstitial Po2, Po2 is) in the soleus and white gastrocnemius during electrically induced twitch contractions (1 Hz, 8V). CS was lower in HF compared with Con (37 ± 1 vs. 44 ± 1 m/min, P < 0.001), but D' was not different (77 ± 8 vs. 69 ± 13 m, P = 0.6). HF reduced FS (23 ± 2 vs. 47 ± 2%, P < 0.001) and increased LVEDP (15 ± 1 vs. 7 ± 1 mmHg, P < 0.001). CS was related to FS (r = 0.72, P = 0.045) and LVEDP (r = -0.75, P = 0.02) only in HF. HF reduced soleus Po2 is at rest and during contractions (both P < 0.01) but had no effect on white gastrocnemius Po2 is (P > 0.05). We show in HF rats that decrements in central cardiac function relate directly with impaired exercise tolerance (i.e., CS) and that this compromised exercise tolerance is likely due to reduced perfusive and diffusive O2 delivery to oxidative muscles.NEW & NOTEWORTHY We show that critical speed (CS), which defines the upper boundary of sustainable activity, can be resolved in heart failure (HF) animals and is diminished compared with controls. Central cardiac function is strongly related with CS in the HF animals, but not controls. Skeletal muscle O2 delivery-to-utilization dysfunction is evident in the more oxidative, but not glycolytic, muscles of HF rats and is explained, in part, by reduced nitric oxide bioavailability.
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Affiliation(s)
- Jesse C Craig
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Jacob T Caldwell
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Daniel M Hirai
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Ayaka Tabuchi
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Dryden R Baumfalk
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Bradley J Behnke
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Carl J Ade
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - 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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33
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Poole DC. Edward F. Adolph Distinguished Lecture. Contemporary model of muscle microcirculation: gateway to function and dysfunction. J Appl Physiol (1985) 2019; 127:1012-1033. [PMID: 31095460 DOI: 10.1152/japplphysiol.00013.2019] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
This review strikes at the very heart of how the microcirculation functions to facilitate blood-tissue oxygen, substrate, and metabolite fluxes in skeletal muscle. Contemporary evidence, marshalled from animals and humans using the latest techniques, challenges iconic perspectives that have changed little over the past century. Those perspectives include the following: the presence of contractile or collapsible capillaries in muscle, unitary control by precapillary sphincters, capillary recruitment at the onset of contractions, and the notion of capillary-to-mitochondrial diffusion distances as limiting O2 delivery. Today a wealth of physiological, morphological, and intravital microscopy evidence presents a completely different picture of microcirculatory control. Specifically, capillary red blood cell (RBC) and plasma flux is controlled primarily at the arteriolar level with most capillaries, in healthy muscle, supporting at least some flow at rest. In healthy skeletal muscle, this permits substrate access (whether carried in RBCs or plasma) to a prodigious total capillary surface area. Pathologies such as heart failure or diabetes decrease access to that exchange surface by reducing the proportion of flowing capillaries at rest and during exercise. Capillary morphology and function vary disparately among tissues. The contemporary model of capillary function explains how, following the onset of exercise, muscle O2 uptake kinetics can be extremely fast in health but slowed in heart failure and diabetes impairing contractile function and exercise tolerance. It is argued that adoption of this model is fundamental for understanding microvascular function and dysfunction and, as such, to the design and evaluation of effective therapeutic strategies to improve exercise tolerance and decrease morbidity and mortality in disease.
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Affiliation(s)
- David C Poole
- Departments of Kinesiology, Anatomy and Physiology, Kansas State University, Manhattan, Kansas
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34
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Craig JC, Colburn TD, Hirai DM, Musch TI, Poole DC. Sexual dimorphism in the control of skeletal muscle interstitial Po 2 of heart failure rats: effects of dietary nitrate supplementation. J Appl Physiol (1985) 2019; 126:1184-1192. [PMID: 30844332 DOI: 10.1152/japplphysiol.01004.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Sex differences in the mechanisms underlying cardiovascular pathophysiology of O2 transport in heart failure (HF) remain to be explored. In HF, nitric oxide (NO) bioavailability is reduced and contributes to deficits in O2 delivery-to-utilization matching. Females may rely more on NO for cardiovascular control and as such experience greater decrements in HF. We tested the hypotheses that moderate HF induced by myocardial infarction would attenuate the skeletal muscle interstitial Po2 response to contractions (Po2is; determined by O2 delivery-to-utilization matching) compared with healthy controls and females would express greater dysfunction than male counterparts. Furthermore, we hypothesized that 5 days of dietary nitrate supplementation (Nitrate; 1 mmol·kg-1·day-1) would raise Po2is in HF rats. Forty-two Sprague-Dawley rats were randomly assigned to healthy, HF, or HF + Nitrate groups (each n = 14; 7 female/7 male). Spinotrapezius Po2is was measured via phosphorescence quenching during electrically induced twitch contractions (180 s; 1 Hz). HF reduced resting Po2is for both sexes compared with healthy controls (P < 0.01), and females were lower than males (14 ± 1 vs. 17 ± 2 mmHg) (P < 0.05). In HF both sexes expressed reduced Po2is amplitudes following the onset of muscle contractions compared with healthy controls (female: -41 ± 7%, male: -26 ± 12%) (P < 0.01). In HF rats, Nitrate elevated resting Po2is to values not different from healthy rats and removed the sex difference. Female HF + Nitrate rats expressed greater resting Po2is and amplitudes compared with female HF (P < 0.05). In this model of moderate HF, O2 delivery-to-utilization matching in the interstitial space is diminished in a sex-specific manner and dietary nitrate supplementation may serve to offset this reduction in HF rats with greater effects in females. NEW & NOTEWORTHY Interstitial Po2 (Po2is; indicative of O2 delivery-to-utilization matching) determines, in part, O2 flux into skeletal muscle. We show that heart failure (HF) reduces Po2is at rest and during skeletal muscle contractions in rats and this negative effect is amplified for females. However, elevating NO bioavailability with dietary nitrate supplementation increases resting Po2is and alters the dynamic response with greater efficacy in female HF rats, particularly at rest and following the onset of muscle contractions.
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Affiliation(s)
- Jesse C Craig
- Department of Kinesiology, Kansas State University , Manhattan, Kansas
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University , Manhattan, Kansas
| | - Daniel M Hirai
- Department of Kinesiology, Kansas State University , Manhattan, Kansas
| | - 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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35
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Clanton TL. Managing the power grid: how myoglobin can regulate PO2 and energy distribution in skeletal muscle. J Appl Physiol (1985) 2019; 126:787-790. [DOI: 10.1152/japplphysiol.00614.2018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Affiliation(s)
- Thomas L. Clanton
- Department of Applied Physiology and Kinesiology, the University of Florida Gainesville, Florida
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36
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Bock JM, Kruse NT, Donnelly C, Hirai DM, Craig JC, Colburn TD, Musch TI, Poole DC, Rosenberry R, Tian F, Liu H, Nelson MD, Piknova B, Willis WT, Zuo L, Zhou T, Riveros-Rivera A, Cristancho E, Gunga HC. Commentaries on Viewpoint: Managing the power grid: How myoglobin can regulate Po 2 and energy distribution in skeletal muscle. J Appl Physiol (1985) 2019; 126:791-794. [PMID: 30907709 DOI: 10.1152/japplphysiol.01107.2018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Joshua M Bock
- Department of Physical Therapy and Rehabilitation Science, University of Iowa, Iowa City, Iowa
| | - Nicholas T Kruse
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Chris Donnelly
- Institute of Sport Sciences and Department of Physiology, University of Lausanne, Switzerland
| | - Daniel M Hirai
- Department of Health and Kinesiology, Purdue University, West Lafayette, Indiana
| | - Jesse C Craig
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah,Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, Utah
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - 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
| | - Ryan Rosenberry
- Department of Kinesiology, University of Texas at Arlington, Texas
| | - Fenghua Tian
- Department of Bioengineering, University of Texas at Arlington, Texas
| | - Hanli Liu
- Department of Bioengineering, University of Texas at Arlington, Texas
| | - Michael D Nelson
- Department of Kinesiology, University of Texas at Arlington, Texas,Department of Bioengineering, University of Texas at Arlington, Texas
| | - Barbora Piknova
- Molecular Medicine Branch, NIDDK National Institutes of Health, Bethesda, Maryland
| | | | - Li Zuo
- Radiologic Sciences and Respiratory Therapy Division, School of Health and Rehabilitation Sciences, The Ohio State University College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio,Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, Ohio,Department of Biology, University of Maine, Presque Isle, Maine
| | - Tingyang Zhou
- Radiologic Sciences and Respiratory Therapy Division, School of Health and Rehabilitation Sciences, The Ohio State University College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio,Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, Ohio
| | - Alain Riveros-Rivera
- Institute of Physiology, Center for Space Medicine and Extreme Environments, Charité - Universitätsmedizin Berlin, Germany
| | - Edgar Cristancho
- Department of Biology. Universidad Nacional de Colombia. Bogotá, Colombia
| | - Hanns-Christian Gunga
- Institute of Physiology, Center for Space Medicine and Extreme Environments, Charité - Universitätsmedizin Berlin, Germany
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37
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Hirai DM, Colburn TD, Craig JC, Hotta K, Kano Y, Musch TI, Poole DC. Skeletal muscle interstitial O 2 pressures: bridging the gap between the capillary and myocyte. Microcirculation 2018; 26:e12497. [PMID: 30120845 DOI: 10.1111/micc.12497] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 07/26/2018] [Accepted: 08/13/2018] [Indexed: 01/18/2023]
Abstract
The oxygen transport pathway from air to mitochondria involves a series of transfer steps within closely integrated systems (pulmonary, cardiovascular, and tissue metabolic). Small and finite O2 stores in most mammalian species require exquisitely controlled changes in O2 flux rates to support elevated ATP turnover. This is especially true for the contracting skeletal muscle where O2 requirements may increase two orders of magnitude above rest. This brief review focuses on the mechanistic bases for increased microvascular blood-myocyte O2 flux (V̇O2 ) from rest to contractions. Fick's law dictates that V̇O2 elevations driven by muscle contractions are produced by commensurate changes in driving force (ie, O2 pressure gradients; ΔPO2 ) and/or effective diffusing capacity (DO2 ). While previous evidence indicates that increased DO2 helps modulate contracting muscle O2 flux, up until recently the role of the dynamic ΔPO2 across the capillary wall was unknown. Recent phosphorescence quenching investigations of both microvascular and novel interstitial PO2 kinetics in health have resolved an important step in the O2 cascade between the capillary and myocyte. Specifically, the significant transmural ΔPO2 at rest was sustained (but not increased) during submaximal contractions. This supports the contention that the blood-myocyte interface provides a substantial effective resistance to O2 diffusion and underscores that modulations in erythrocyte hemodynamics and distribution (DO2 ) are crucial to preserve the driving force for O2 flux across the capillary wall (ΔPO2 ) during contractions. Investigation of the O2 transport pathway close to muscle mitochondria is key to identifying disease mechanisms and develop therapeutic approaches to ameliorate dysfunction and exercise intolerance.
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Affiliation(s)
- Daniel M Hirai
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
| | - Trenton D Colburn
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
| | - Jesse C Craig
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
| | - Kazuki Hotta
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - Yutaka Kano
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - Timothy I Musch
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
| | - David C Poole
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
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38
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Arana C, Swanson B, Kuzyk SL. Probing under pressure: a look inside the compartmental haemodynamics of skeletal muscle during rest and contraction. J Physiol 2018; 596:2035-2036. [PMID: 29645273 DOI: 10.1113/jp276078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Carolina Arana
- School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
| | - Brittney Swanson
- School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
| | - Samantha L Kuzyk
- School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
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39
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Craig JC, Colburn TD, Hirai DM, Schettler MJ, Musch TI, Poole DC. Sex and nitric oxide bioavailability interact to modulate interstitial Po 2 in healthy rat skeletal muscle. J Appl Physiol (1985) 2018; 124:1558-1566. [PMID: 29369738 DOI: 10.1152/japplphysiol.01022.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Premenopausal women express reduced blood pressure and risk of cardiovascular disease relative to age-matched men. This purportedly relates to elevated estrogen levels increasing nitric oxide synthase (NOS) activity and NO-mediated vasorelaxation. We tested the hypotheses that female rat skeletal muscle would: 1) evince a higher O2 delivery-to-utilization ratio (Q̇o2/V̇o2) during contractions; and 2) express greater modulation of Q̇o2/V̇o2 with changes to NO bioavailability compared with male rats. The spinotrapezius muscle of Sprague-Dawley rats (females = 8, males = 8) was surgically exposed and electrically-stimulated (180 s, 1 Hz, 6 V). OxyphorG4 was injected into the muscle and phosphorescence quenching employed to determine the temporal profile of interstitial Po2 (Po2is, determined by Q̇o2/V̇o2). This was performed under three conditions: control (CON), 300 µM sodium nitroprusside (SNP; NO donor), and 1.5 mM Nω-nitro-l-arginine methyl ester (l-NAME; NOS blockade) superfusion. No sex differences were found for the Po2is kinetics parameters in CON or l-NAME ( P > 0.05), but females elicited a lower baseline following SNP (males 42 ± 3 vs. females 36 ± 2 mmHg, P < 0.05). Females had a lower ΔPo2is during contractions following SNP (males 22 ± 3 vs. females 17 ± 2 mmHg, P < 0.05), but there were no sex differences for the temporal response to contractions ( P > 0.05). The total NO effect (SNP minus l-NAME) on Po2is was not different between sexes. However, the spread across both conditions was shifted to a lower absolute range for females (reduced SNP baseline and greater reduction following l-NAME). These data support that females have a greater reliance on basal NO bioavailability and males have a greater responsiveness to exogenous NO and less responsiveness to reduced endogenous NO. NEW & NOTEWORTHY Interstitial Po2 (Po2is; determined by O2 delivery-to-utilization matching) plays an important role for O2 flux into skeletal muscle. We show that both sexes regulate Po2is at similar levels at rest and during skeletal muscle contractions. However, modulating NO bioavailability exposes sex differences in this regulation with females potentially having a greater reliance on basal NO bioavailability and males having a greater responsiveness to exogenous NO and less responsiveness to reduced endogenous NO.
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Affiliation(s)
- Jesse C Craig
- Department of Kinesiology, Kansas State University , Manhattan, Kansas
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University , Manhattan, Kansas
| | - Daniel M Hirai
- Department of Kinesiology, Kansas State University , Manhattan, Kansas
| | - Michael J Schettler
- Department of Anatomy and Physiology, Kansas State University , Manhattan, Kansas
| | - 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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