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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: 17] [Impact Index Per Article: 8.5] [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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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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Smith JR, Hirai DM, Copp SW, Ferguson SK, Holdsworth CT, Hageman KS, Poole DC, Musch TI. Exercise training decreases intercostal and transversus abdominis muscle blood flows in heart failure rats during submaximal exercise. Respir Physiol Neurobiol 2021; 292:103710. [PMID: 34091075 DOI: 10.1016/j.resp.2021.103710] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/18/2021] [Accepted: 06/02/2021] [Indexed: 11/30/2022]
Abstract
Diaphragm muscle blood flow (BF) and vascular conductance (VC) are elevated with chronic heart failure (HF) during exercise. Exercise training (ExT) elicits beneficial respiratory muscle and pulmonary system adaptations in HF. We hypothesized that diaphragm BF and VC would be lower in HF rats following ExT than their sedentary counterparts (Sed). Respiratory muscle BFs and mean arterial pressure were measured via radiolabeled microspheres and carotid artery catheter, respectively, during submaximal treadmill exercise (20 m/min, 5 % grade). During exercise, no differences were present between HF + ExT and HF + Sed in diaphragm BFs (201 ± 36 vs. 227 ± 44 mL/min/100 g) or VCs (both, p > 0.05). HF + ExT compared to HF + Sed had lower intercostal BF (27 ± 3 vs. 41 ± 5 mL/min/100 g) and VC (0.21 ± 0.02 vs. 0.31 ± 0.04 mL/min/mmHg/100 g) during exercise (both, p < 0.05). Further, HF + ExT compared to HF + Sed had lower transversus abdominis BF (20 ± 1 vs. 35 ± 6 mL/min/100 g) and VC (0.14 ± 0.02 vs. 0.27 ± 0.05 mL/min/mmHg/100 g) during exercise (both, p < 0.05). These data suggest that exercise training lowers the intercostal and transversus abdominis BF responses in HF rats during submaximal treadmill exercise.
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Affiliation(s)
- Joshua R Smith
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States.
| | - Daniel M Hirai
- Department of Health and Kinesiology, Purdue University, West Lafayette, IN, United States
| | - Steven W Copp
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States
| | - Scott K Ferguson
- Department of Kinesiology and Exercise Sciences, University of Hawaii, Hilo, HI, United States
| | - Clark T Holdsworth
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States
| | - K Sue Hageman
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States
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4
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Mendelson AA, Milkovich S, Hunter T, Vijay R, Choi YH, Milkovich S, Ho E, Goldman D, Ellis CG. The capillary fascicle in skeletal muscle: Structural and functional physiology of RBC distribution in capillary networks. J Physiol 2021; 599:2149-2168. [PMID: 33595111 DOI: 10.1113/jp281172] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/04/2021] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS The capillary module, consisting of parallel capillaries from arteriole to venule, is classically considered as the building block of complex capillary networks. In skeletal muscle, this structure fails to address how blood flow is regulated along the entire length of the synchronously contracting muscle fibres. Using intravital video microscopy of resting extensor digitorum longus muscle in rats, we demonstrated the capillary fascicle as a series of interconnected modules forming continuous columns that align naturally with the dimensions of the muscle fascicle. We observed structural heterogeneity for module topology, and functional heterogeneity in space and time for capillary-red blood cell (RBC) haemodynamics within a module and between modules. We found that module RBC haemodynamics were independent of module resistance, providing direct evidence for microvascular flow regulation at the level of the capillary module. The capillary fascicle is an updated paradigm for characterizing blood flow and RBC distribution in skeletal muscle capillary networks. ABSTRACT Capillary networks are the fundamental site of oxygen exchange in the microcirculation. The capillary module (CM), consisting of parallel capillaries from terminal arteriole (TA) to post-capillary venule (PCV), is classically considered as the building block of complex capillary networks. In skeletal muscle, this structure fails to address how blood flow is regulated along the entire length of the synchronously contracting muscle fibres, requiring co-ordination from numerous modules. It has previously been recognized that TAs and PCVs interact with multiple CMs, creating interconnected networks. Using label-free intravital video microscopy of resting extensor digitorum longus muscle in rats, we found that these networks form continuous columns of linked CMs spanning thousands of microns, herein denoted as the capillary fascicle (CF); this structure aligns naturally with the dimensions of the muscle fascicle. We measured capillary-red blood cell (RBC) haemodynamics and module topology (n = 9 networks, 327 modules, 1491 capillary segments). The average module had length 481 μm, width 157 μm and 9.51 parallel capillaries. We observed structural heterogeneity for CM topology, and functional heterogeneity in space and time for capillary-RBC haemodynamics within a module and between modules. There was no correlation between capillary RBC velocity and lineal density. A passive inverse relationship between module length and haemodynamics was remarkably absent, providing direct evidence for microvascular flow regulation at the level of the CM. In summary, the CF is an updated paradigm for characterizing RBC distribution in skeletal muscle, and strengthens the theory of capillary networks as major contributors to the signal that regulates capillary perfusion.
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Affiliation(s)
- Asher A Mendelson
- Department of Medicine, Section of Critical Care Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Stephanie Milkovich
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Timothy Hunter
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Raashi Vijay
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Yun-Hee Choi
- Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Shaun Milkovich
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Edward Ho
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Daniel Goldman
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.,Department of Applied Mathematics, Faculty of Science, Western University, London, Ontario, Canada
| | - Christopher G Ellis
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.,Robarts Research Institute, London, Ontario, Canada
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Poole DC, 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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6
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Hirai DM, Craig JC, Colburn TD, Eshima H, Kano Y, Musch TI, Poole DC. Skeletal muscle interstitial Po 2 kinetics during recovery from contractions. J Appl Physiol (1985) 2019; 127:930-939. [PMID: 31369325 DOI: 10.1152/japplphysiol.00297.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The oxygen partial pressure in the interstitial space (Po2 is) drives O2 into the myocyte via diffusion, thus supporting oxidative phosphorylation. Although crucial for metabolic recovery and the capacity to perform repetitive tasks, the time course of skeletal muscle Po2 is during recovery from contractions remains unknown. We tested the hypothesis that Po2 is would recover to resting values and display considerable on-off asymmetry (fast on-, slow off-kinetics), reflective of asymmetric capillary hemodynamics. Microvascular Po2 (Po2 mv) was also evaluated to test the hypothesis that a significant transcapillary gradient (ΔPo2 = Po2 mv - Po2 is) would be sustained during recovery. Po2 mv and Po2 is (expressed in mmHg) were determined via phosphorescence quenching in the exposed rat spinotrapezius muscle during and after submaximal twitch contractions (n = 12). Po2 is rose exponentially (P < 0.05) from end-contraction (11.1 ± 5.1), such that the end-recovery value (17.9 ± 7.9) was not different from resting Po2 is (18.5 ± 8.1; P > 0.05). Po2 is off-kinetics were slower than on-kinetics (mean response time: 53.1 ± 38.3 versus 18.5 ± 7.3 s; P < 0.05). A significant transcapillary ΔPo2 observed at end-contraction (16.6 ± 7.4) was maintained throughout recovery (end-recovery: 18.8 ± 9.6; P > 0.05). Consistent with our hypotheses, muscle Po2 is recovered to resting values with slower off-kinetics compared with the on-transient in line with the on-off asymmetry for capillary hemodynamics. Maintenance of a substantial transcapillary ΔPo2 during recovery supports that the microvascular-interstitium interface provides considerable resistance to O2 transport. As dictated by Fick's law (V̇o2 = Do2 × ΔPo2), modulation of O2 flux (V̇o2) during recovery must be achieved via corresponding changes in effective diffusing capacity (Do2; mainly capillary red blood cell hemodynamics and distribution) in the face of unaltered ΔPo2.NEW & NOTEWORTHY Capillary blood-myocyte O2 flux (V̇o2) is determined by effective diffusing capacity (Do2; mainly erythrocyte hemodynamics and distribution) and microvascular-interstitial Po2 gradients (ΔPo2 = Po2 mv - Po2 is). We show that Po2 is demonstrates on-off asymmetry consistent with Po2 mv and erythrocyte kinetics during metabolic transitions. A substantial transcapillary ΔPo2 was preserved during recovery from contractions, indicative of considerable resistance to O2 diffusion at the microvascular-interstitium interface. This reveals that effective Do2 declines in step with V̇o2 during recovery, as per Fick's law.
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Affiliation(s)
- Daniel M Hirai
- Department of Health and Kinesiology, Purdue University, West Lafayette, Indiana.,Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Jesse C Craig
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas.,Department of Internal Medicine, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Hiroaki Eshima
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Yutaka Kano
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
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7
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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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8
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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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9
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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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10
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Niemeijer VM, Snijders T, Verdijk LB, van Kranenburg J, Groen BBL, Holwerda AM, Spee RF, Wijn PFF, van Loon LJC, Kemps HMC. Skeletal muscle fiber characteristics in patients with chronic heart failure: impact of disease severity and relation with muscle oxygenation during exercise. J Appl Physiol (1985) 2018; 125:1266-1276. [PMID: 30091667 DOI: 10.1152/japplphysiol.00057.2018] [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: 12/30/2022] Open
Abstract
INTRODUCTION Skeletal muscle function in patients with heart failure and reduced ejection fraction (HFrEF) greatly determines exercise capacity. However, reports on skeletal muscle fiber dimensions, fiber capillarization, and their physiological importance are inconsistent. METHODS Twenty-five moderately-impaired patients with HFrEF and 25 healthy control (HC) subjects underwent muscle biopsy sampling. Type I and type II muscle fiber characteristics were determined by immunohistochemistry. In patients with HFrEF, enzymatic oxidative capacity was assessed, and pulmonary oxygen uptake (VO2) and skeletal muscle oxygenation during maximal and moderate-intensity exercise were measured using near-infrared spectroscopy. RESULTS While muscle fiber cross-sectional area (CSA) was not different between patients with HFrEF and HC, percentage of type I fibers was higher in HC (46±15% versus 37±12%, respectively, P=0.041). Fiber type distribution and CSA were not different between patients in New York Heart Association (NYHA) class II and III. Type I muscle fiber capillarization was higher in HFrEF compared with controls (capillary-to-fiber perimeter exchange (CFPE) index: 5.70±0.92 versus 5.05±0.82, respectively, P=0.027). Patients in NYHA class III had slower VO2 and muscle deoxygenation kinetics during onset of exercise, and lower muscle oxidative capacity than those in class II (P<0.05). Also, fiber capillarization was lower, but not compared with HC. Higher CFPE index was related to faster deoxygenation (rspearman=-0.682, P=0.001), however, not to muscle oxidative capacity (r=-0.282, P=0.216). CONCLUSIONS Type I muscle fiber capillarization is higher in HFrEF compared with HC, but not in patients with greater exercise impairment. Greater capillarization may positively affect VO2 kinetics by enhancing muscle oxygen diffusion.
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Affiliation(s)
- Victor M Niemeijer
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands, Netherlands
| | - Tim Snijders
- Human Movement Sciences, Maastricht University Medical Centre+, Netherlands
| | - Lex B Verdijk
- Human Movement Sciences, Maastricht University Medical Centre, Netherlands
| | - Janneau van Kranenburg
- Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+ (MUMC+)
| | - Bart B L Groen
- Department of Human Movement Sciences, Maastricht University Medical Centre, Netherlands
| | | | - Ruud F Spee
- Department of Cardiology, Maxima Medical Center, Netherlands
| | - Pieter F F Wijn
- Department of Applied Physics, Eindhoven University of Technology
| | - Luc J C van Loon
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Netherlands
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11
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Koschate J, Thieschäfer L, Drescher U, Hoffmann U. Impact of 60 days of 6° head down tilt bed rest on muscular oxygen uptake and heart rate kinetics: efficacy of a reactive sledge jump countermeasure. Eur J Appl Physiol 2018; 118:1885-1901. [PMID: 29946969 DOI: 10.1007/s00421-018-3915-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 06/08/2018] [Indexed: 01/06/2023]
Abstract
PURPOSE The effects of 60 days of head down tilt bed rest (HDBR) with and without the application of a reactive jump countermeasure were investigated, using a method which enables to discriminate between pulmonary ([Formula: see text]O2pulm) and muscular ([Formula: see text]O2musc) oxygen uptake kinetics to control for hemodynamic influences. METHODS 22 subjects were randomly allocated to either a group performing a reactive jumps countermeasure (JUMP; n = 11, male, 29 ± 7 years, 23.9 ± 1.3 kg m- 2) or a control group (CTRL; n = 11, male, 29 ± 6 years, 23.3 ± 2.0 kg m- 2). Heart rate (HR) and [Formula: see text]O2pulm were measured in response to repeated changes in work rate between 30 and 80 W before (BDC-9) and two times after HDBR (R+ 2, R+ 13). Kinetic responses of HR, [Formula: see text]O2pulm, and [Formula: see text]O2musc were assessed applying time series analysis. Higher maxima in cross-correlation functions (CCFmax(x)) between work rate and the respective parameter indicate faster kinetics responses. Statistical analysis was performed applying multifactorial analysis of variance. RESULTS CCFmax([Formula: see text]O2musc) and CCFmax([Formula: see text]O2pulm) were not significantly different before and after HDBR (P > 0.05). CCFmax(HR) decreased following bed rest (JUMP: BDC-9: 0.30 ± 0.09 vs. R+ 2: 0.28 ± 0.06 vs. R+13: 0.28 ± 0.07; CTRL: 0.35 ± 0.09 vs. 0.27 ± 0.06 vs. 0.33 ± 0.07 P = 0.025). No significant differences between the groups were observed (P > 0.05). Significant alterations were found for CCFmax of mean arterial blood pressure (mBP) after HDBR (JUMP: BDC-9: 0.21 ± 0.07 vs. R+ 2: 0.30 ± 0.13 vs. R+ 13: 0.28 ± 0.08; CTRL: 0.25 ± 0.07 vs. 0.38 ± 0.13 vs. 0.28 ± 0.08; P = 0.008). CONCLUSIONS Despite hemodynamic changes, [Formula: see text]O2 kinetics seem to be preserved for a longer period of HDBR, even without the application of a countermeasure.
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Affiliation(s)
- J Koschate
- Institute of Physiology and Anatomy, German Sport University Cologne, Am Sportpark Muengersdorf 6, 50933, Cologne, Germany.
| | - L Thieschäfer
- Institute of Physiology and Anatomy, German Sport University Cologne, Am Sportpark Muengersdorf 6, 50933, Cologne, Germany
| | - U Drescher
- Institute of Physiology and Anatomy, German Sport University Cologne, Am Sportpark Muengersdorf 6, 50933, Cologne, Germany
| | - U Hoffmann
- Institute of Physiology and Anatomy, German Sport University Cologne, Am Sportpark Muengersdorf 6, 50933, Cologne, Germany
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Apeke S, Gaubert L, Boussion N, Lambin P, Visvikis D, Rodin V, Redou P. Multi-Scale Modeling and Oxygen Impact on Tumor Temporal Evolution: Application on Rectal Cancer During Radiotherapy. IEEE TRANSACTIONS ON MEDICAL IMAGING 2018; 37:871-880. [PMID: 29610067 DOI: 10.1109/tmi.2017.2771379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We present a multi-scale approach of tumor modeling in order to predict its evolution during radiotherapy. Within this context we focus on three different scales of tumor modeling: microscopic (individual cells in a voxel), mesoscopic (population of cells in a voxel) and macroscopic (whole tumor), with transition interfaces between these three scales. At the cellular level, the description is based on phase transfer probabilities in the cellular cycle. At the mesoscopic scale we represent populations of cells according to different stages in a cell cycle. Finally, at the macroscopic scale, the tumor description is based on the use of FDG PET image voxels. These three scales exist naturally: biological data are collected at the macroscopic scale, but the pathological behavior of the tumor is based on an abnormal cell-cycle at the microscopic scale. On the other hand, the introduction of a mesoscopic scale is essential in order to reduce the gap between the two extreme, in terms of resolution, description levels. It also reduces the computational burden of simulating a large number of individual cells. As an application of the proposed multi-scale model, we simulate the effect of oxygen on tumor evolution during radiotherapy. Two consecutive FDG PET images of 17 rectal cancer patients undergoing radiotherapy are used to simulate the tumor evolution during treatment. The simulated results are compared with those obtained on a third FDG PET image acquired two weeks after the beginning of the treatment.
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Jalil B, Hartwig V, Salvetti O, Potì L, Gargani L, Barskova T, Matucci Cerinic M, L'Abbate A. Assessment of hand superficial oxygenation during ischemia/reperfusion in healthy subjects versus systemic sclerosis patients by 2D near infrared spectroscopic imaging. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2018; 155:101-108. [PMID: 29512489 DOI: 10.1016/j.cmpb.2017.12.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 11/03/2017] [Accepted: 12/11/2017] [Indexed: 06/08/2023]
Abstract
BACKGROUND AND OBJECTIVE Patients affected by systemic sclerosis (SSc) develop functional and structural microcirculatory dysfunction, which progressively evolves towards systemic tissue fibrosis (sclerosis). Disease initially affects distal extremities, which become preferential sites of diagnostic scrutiny. This pilot investigation tested the hypothesis that peripheral microcirculatory dysfunction in SSc could be non-invasively assessed by 2D Near Infrared Spectroscopic (NIRS) imaging of the hand associated with Vascular Occlusion Testing (VOT). NIRS allows measurement of hemoglobin oxygen saturation (StO2) in the blood perfusing the volume tissue under scrutiny. METHODS In five normal volunteers and five SSc patients we applied a multispectral oximetry imaging device (Kent camera, Kent Imaging, Calgary, Canada) to acquire StO2 2D maps of the whole hand palm during baseline, ischemia and reperfusion phase. RESULTS We found significant differences between controls and SSc patients in basal StO2 (82.80 ± 2.51 vs 65.44 ± 7.96%, p = 0.0016), minimum StO2 (59.35 ± 4.29 vs 40.73 ± 6.47%, p = 0.0007), final StO2 (83.83 ± 4.09 vs 68.84 ± 11.41%, p = 0.02) and time to maximum StO2 (40 ± 12.25 vs 62 ± 4.47 s, p = 0.005). CONCLUSIONS This is, to our knowledge, the first application of 2D NIRS imaging of the whole hand to the investigation of microvascular dysfunction in systemic sclerosis. The image processing presented here considered the StO2 in the entire hand allowing a comprehensive view of the spatial heterogeneity of microvascular dysfunction.
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Affiliation(s)
- Bushra Jalil
- Istituto di Scienza e Tecnologie dell'Informazione "Alessandro Faedo" CNR, Via Moruzzi 1, 56124 Pisa, Italy
| | - Valentina Hartwig
- Institute of Clinical Physiology, Italian National Research Council (CNR), Via Moruzzi 1, 56124 Pisa, Italy.
| | - Ovidio Salvetti
- Istituto di Scienza e Tecnologie dell'Informazione "Alessandro Faedo" CNR, Via Moruzzi 1, 56124 Pisa, Italy
| | - Luca Potì
- Consorzio Nazionale Interuniversitario per le Telecomunicazioni, Pisa, Italy
| | - Luna Gargani
- Institute of Clinical Physiology, Italian National Research Council (CNR), Via Moruzzi 1, 56124 Pisa, Italy
| | - Tatiana Barskova
- Department of Experimental and Clinical Medicine, Division of Rheumatology AOUC, University of Florence, Florence, Italy
| | - Marco Matucci Cerinic
- Department of Experimental and Clinical Medicine, Division of Rheumatology AOUC, University of Florence, Florence, Italy
| | - A L'Abbate
- Institute of Clinical Physiology, Italian National Research Council (CNR), Via Moruzzi 1, 56124 Pisa, Italy; Scuola Superiore Sant'Anna, Institute of Life Sciences, Piazza Martiri della Libertà 33, 56127 Pisa, Italy
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Hirai DM, Craig JC, Colburn TD, Eshima H, Kano Y, Sexton WL, Musch TI, Poole DC. Skeletal muscle microvascular and interstitial PO2 from rest to contractions. J Physiol 2018; 596:869-883. [PMID: 29288568 DOI: 10.1113/jp275170] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 12/01/2017] [Indexed: 01/21/2023] Open
Abstract
KEY POINTS Oxygen pressure gradients across the microvascular walls are essential for oxygen diffusion from blood to tissue cells. At any given flux, the magnitude of these transmural gradients is proportional to the local resistance. The greatest resistance to oxygen transport into skeletal muscle is considered to reside in the short distance between red blood cells and myocytes. Although crucial to oxygen transport, little is known about transmural pressure gradients within skeletal muscle during contractions. We evaluated oxygen pressures within both the skeletal muscle microvascular and interstitial spaces to determine transmural gradients during the rest-contraction transient in anaesthetized rats. The significant transmural gradient observed at rest was sustained during submaximal muscle contractions. Our findings support that the blood-myocyte interface provides substantial resistance to oxygen diffusion at rest and during contractions and suggest that modulations in microvascular haemodynamics and red blood cell distribution constitute primary mechanisms driving increased transmural oxygen flux with contractions. ABSTRACT Oxygen pressure (PO2) gradients across the blood-myocyte interface are required for diffusive O2 transport, thereby supporting oxidative metabolism. The greatest resistance to O2 flux into skeletal muscle is considered to reside between the erythrocyte surface and adjacent sarcolemma, although this has not been measured during contractions. We tested the hypothesis that O2 gradients between skeletal muscle microvascular (PO2 mv ) and interstitial (PO2 is ) spaces would be present at rest and maintained or increased during contractions. PO2 mv and PO2 is were determined via phosphorescence quenching (Oxyphor probes G2 and G4, respectively) in the exposed rat spinotrapezius during the rest-contraction transient (1 Hz, 6 V; n = 8). PO2 mv was higher than PO2 is in all instances from rest (34.9 ± 6.0 versus 15.7 ± 6.4) to contractions (28.4 ± 5.3 versus 10.6 ± 5.2 mmHg, respectively) such that the mean PO2 gradient throughout the transient was 16.9 ± 6.6 mmHg (P < 0.05 for all). No differences in the amplitude of PO2 fall with contractions were observed between the microvasculature and interstitium (10.9 ± 2.3 versus 9.0 ± 3.5 mmHg, respectively; P > 0.05). However, the speed of the PO2 is fall during contractions was slower than that of PO2 mv (time constant: 12.8 ± 4.7 versus 9.0 ± 5.1 s, respectively; P < 0.05). Consistent with our hypothesis, a significant transmural gradient was sustained (but not increased) from rest to contractions. This supports that the blood-myocyte interface is the site of a substantial PO2 gradient driving O2 diffusion during metabolic transients. Based on Fick's law, elevated O2 flux with contractions must thus rely primarily on modulations in effective diffusing capacity (mainly erythrocyte haemodynamics and distribution) as the PO2 gradient is not increased.
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Affiliation(s)
- Daniel M Hirai
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Jesse C Craig
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Trenton D Colburn
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Hiroaki Eshima
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - Yutaka Kano
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - William L Sexton
- Department of Physiology, A.T. Still University of Health Sciences, Kirksville, MO, USA
| | - Timothy I Musch
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - David C Poole
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
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15
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Neuronal nitric oxide synthase regulation of skeletal muscle functional hyperemia: exercise training and moderate compensated heart failure. Nitric Oxide 2017; 74:1-9. [PMID: 29288804 DOI: 10.1016/j.niox.2017.12.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 11/15/2017] [Accepted: 12/24/2017] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) modulates oxygen delivery-utilization matching in resting and contracting skeletal muscle. Recent reports indicate that neuronal NO synthase (nNOS)-mediated vasoregulation during contractions is enhanced with exercise training and impaired with chronic heart failure (HF). Consequently, we tested the hypothesis that selective nNOS inhibition (S-methyl-l-thiocitrulline; SMTC, 2.1 μmol/kg) would produce attenuated reductions in muscle blood flow during moderate/heavy submaximal exercise in sedentary HF rats compared to their healthy counterparts. In addition, SMTC was expected to evoke greater reductions in exercising muscle blood flow in trained compared to sedentary healthy and HF rats. Blood flow during submaximal treadmill running (20 min/m, 5% grade) was determined via radiolabeled microspheres pre- and post-SMTC administration in healthy sedentary (Healthy + Sed, n = 8), healthy exercise trained (Healthy + ExT, n = 8), HF sedentary (HF + Sed, left ventricular end-diastolic pressure (LVEDP) = 12 ± 1 mmHg, n = 8), and HF exercise trained (HF + ExT, LVEDP = 16 ± 2 mmHg, n = 7) rats. nNOS contribution to exercising total hindlimb blood flow (ml/min/100 g) was not increased by training in either healthy or HF groups (Healthy + Sed: 105 ± 11 vs. 108 ± 16; Healthy + ExT: 96 ± 9 vs. 91 ± 7; HF + Sed: 124 ± 6 vs. 110 ± 12; HF + ExT: 107 ± 13 vs. 101 ± 8; control vs. SMTC, respectively; p > .05 for all). Similarly, SMTC did not reduce exercising blood flow in the majority of individual hindlimb muscles in any group (p > .05 for all, except for the semitendinosus and adductor longus in HF + Sed and the adductor longus in HF + ExT; p < .05). Contrary to our hypothesis, we find no support for either upregulation of nNOS function contributing to exercise hyperemia after training or its dysregulation with chronic HF.
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Hentschke VS, Capalonga L, Rossato DD, Perini JL, Alves JP, Quagliotto E, Stefani GP, Karsten M, Pontes M, Dal Lago P. Functional capacity in a rat model of heart failure: impact of myocardial infarct size. Exp Physiol 2017; 102:1448-1458. [DOI: 10.1113/ep086076] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 08/21/2017] [Indexed: 01/09/2023]
Affiliation(s)
- Vítor Scotta Hentschke
- Laboratório de Fisiologia; Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA); Porto Alegre Rio Grande do Sul Brazil
- Programa de Pós-Graduação em Ciências da Saúde; Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA); Porto Alegre Rio Grande do Sul Brazil
| | - Lucas Capalonga
- Laboratório de Fisiologia; Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA); Porto Alegre Rio Grande do Sul Brazil
| | - Douglas Dalcin Rossato
- Laboratório de Fisiologia; Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA); Porto Alegre Rio Grande do Sul Brazil
- Centro Universitário Franciscano (UNIFRA); Santa Maria Rio Grande do Sul Brazil
| | - Júlia Luíza Perini
- Laboratório de Fisiologia; Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA); Porto Alegre Rio Grande do Sul Brazil
| | - Jadson Pereira Alves
- Laboratório de Fisiologia; Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA); Porto Alegre Rio Grande do Sul Brazil
- Programa de Pós-Graduação em Ciências da Saúde; Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA); Porto Alegre Rio Grande do Sul Brazil
| | - Edson Quagliotto
- Laboratório de Fisiologia; Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA); Porto Alegre Rio Grande do Sul Brazil
| | - Giuseppe Potrick Stefani
- Laboratório de Fisiologia; Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA); Porto Alegre Rio Grande do Sul Brazil
- Programa de Pós-Graduação em Ciências da Saúde; Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA); Porto Alegre Rio Grande do Sul Brazil
| | - Marlus Karsten
- Departamento de Fisioterapia; Universidade do Estado de Santa Catarina (UDESC); Florianópolis Santa Catarina Brazil
| | - Mauro Pontes
- Departamento de Farmacociências; Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA); Porto Alegre Rio Grande do Sul Brazil
| | - Pedro Dal Lago
- Laboratório de Fisiologia; Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA); Porto Alegre Rio Grande do Sul Brazil
- Departamento de Fisioterapia; Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA); Porto Alegre Rio Grande do Sul Brazil
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Poole DC, Richardson RS, Haykowsky MJ, Hirai DM, Musch TI. Exercise limitations in heart failure with reduced and preserved ejection fraction. J Appl Physiol (1985) 2017; 124:208-224. [PMID: 29051336 DOI: 10.1152/japplphysiol.00747.2017] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The hallmark symptom of chronic heart failure (HF) is severe exercise intolerance. Impaired perfusive and diffusive O2 transport are two of the major determinants of reduced physical capacity and lowered maximal O2 uptake in patients with HF. It has now become evident that this syndrome manifests at least two different phenotypic variations: heart failure with preserved or reduced ejection fraction (HFpEF and HFrEF, respectively). Unlike HFrEF, however, there is currently limited understanding of HFpEF pathophysiology, leading to a lack of effective pharmacological treatments for this subpopulation. This brief review focuses on the disturbances within the O2 transport pathway resulting in limited exercise capacity in both HFpEF and HFrEF. Evidence from human and animal research reveals HF-induced impairments in both perfusive and diffusive O2 conductances identifying potential targets for clinical intervention. Specifically, utilization of different experimental approaches in humans (e.g., small vs. large muscle mass exercise) and animals (e.g., intravital microscopy and phosphorescence quenching) has provided important clues to elucidating these pathophysiological mechanisms. Adaptations within the skeletal muscle O2 delivery-utilization system following established and emerging therapies (e.g., exercise training and inorganic nitrate supplementation, respectively) are discussed. Resolution of the underlying mechanisms of skeletal muscle dysfunction and exercise intolerance is essential for the development and refinement of the most effective treatments for patients with HF.
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Barroco AC, Sperandio PA, Reis M, Almeida DR, Neder JA. A practical approach to assess leg muscle oxygenation during ramp-incremental cycle ergometry in heart failure. ACTA ACUST UNITED AC 2017; 50:e6327. [PMID: 28977120 PMCID: PMC5625546 DOI: 10.1590/1414-431x20176327] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 07/24/2017] [Indexed: 12/05/2022]
Abstract
Heart failure is characterized by the inability of the cardiovascular system to maintain oxygen (O2) delivery (i.e., muscle blood flow in non-hypoxemic patients) to meet O2 demands. The resulting increase in fractional O2 extraction can be non-invasively tracked by deoxygenated hemoglobin concentration (deoxi-Hb) as measured by near-infrared spectroscopy (NIRS). We aimed to establish a simplified approach to extract deoxi-Hb-based indices of impaired muscle O2 delivery during rapidly-incrementing exercise in heart failure. We continuously probed the right vastus lateralis muscle with continuous-wave NIRS during a ramp-incremental cardiopulmonary exercise test in 10 patients (left ventricular ejection fraction <35%) and 10 age-matched healthy males. Deoxi-Hb is reported as % of total response (onset to peak exercise) in relation to work rate. Patients showed lower maximum exercise capacity and O2 uptake-work rate than controls (P<0.05). The deoxi-Hb response profile as a function of work rate was S-shaped in all subjects, i.e., it presented three distinct phases. Increased muscle deoxygenation in patients compared to controls was demonstrated by: i) a steeper mid-exercise deoxi-Hb-work rate slope (2.2±1.3 vs 1.0±0.3% peak/W, respectively; P<0.05), and ii) late-exercise increase in deoxi-Hb, which contrasted with stable or decreasing deoxi-Hb in all controls. Steeper deoxi-Hb-work rate slope was associated with lower peak work rate in patients (r=–0.73; P=0.01). This simplified approach to deoxi-Hb interpretation might prove useful in clinical settings to quantify impairments in O2 delivery by NIRS during ramp-incremental exercise in individual heart failure patients.
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Affiliation(s)
- A C Barroco
- Disciplina de Cardiologia, Universidade Federal de São Paulo, São Paulo, SP, Brasil.,Setor de Fisiologia Clínica do Exercício, Disciplina de Pneumologia, Universidade Federal de São Paulo, São Paulo, SP, Brasil
| | - P A Sperandio
- Disciplina de Cardiologia, Universidade Federal de São Paulo, São Paulo, SP, Brasil.,Departamento de Cardiologia, Instituto Dante Pazzanese de Cardiologia, São Paulo, SP, Brasil.,Setor de Fisiologia Clínica do Exercício, Disciplina de Pneumologia, Universidade Federal de São Paulo, São Paulo, SP, Brasil
| | - M Reis
- Departamento de Fisioterapia, Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - D R Almeida
- Disciplina de Cardiologia, Universidade Federal de São Paulo, São Paulo, SP, Brasil
| | - J A Neder
- Laboratory of Clinical Exercise Physiology, Division of Respiratory and Critical Care Medicine, Queen's University, Kingston, ON, Canada
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Watanabe A, Poole DC, Kano Y. The effects of RSR13 on microvascular Po2 kinetics and muscle contractile performance in the rat arterial ligation model of peripheral arterial disease. J Appl Physiol (1985) 2017; 123:764-772. [DOI: 10.1152/japplphysiol.00257.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 05/17/2017] [Accepted: 06/08/2017] [Indexed: 01/12/2023] Open
Abstract
Exercise intolerance and claudication are symptomatic of peripheral arterial disease. There is a close relationship between muscle O2 delivery, microvascular oxygen partial pressure (P mvO2), and contractile performance. We therefore hypothesized that a reduction of hemoglobin-oxygen affinity via RSR13 would maintain a higher P mvO2 and enhance blood-muscle O2 transport and contractile function. In male Wistar rats (12 wk of age), we created hindlimb ischemia via right-side iliac artery ligation (AL). The contralateral (left) muscle served as control (CONT). Seven days after AL, phosphorescence-quenching techniques were used to measure P mvO2 at rest and during contractions (electrical stimulation; 1 Hz, 300 s) in tibialis anterior muscle (TA) under saline ( n = 10) or RSR13 ( n = 10) conditions. RSR13 at rest increased TA P mvO2 in CONT (13.9 ± 1.6 to 19.3 ± 1.9 Torr, P < 0.05) and AL (9.0 ± 0.5 to 9.9 ± 0.7 Torr, P < 0.05). Furthermore, RSR13 extended maintenance of the initial TA force (i.e., improved contractile performance) such that force was not decreased significantly until contraction 240 vs. 150 in CONT and 80 vs. 20 in AL. This improved muscle endurance with RSR13 was accompanied by a greater ΔP mvO2 (P mvO2 decrease from baseline) (CONT, 7.4 ± 1.0 to 11.2 ± 1.3; AL, 6.9 ± 0.5 to 8.6 ± 0.6 Torr, both P < 0.05). Whereas RSR13 did not alter the kinetics profile of P mvO2 (i.e., mean response time) substantially during contractions, muscle force was elevated, and the ratio of muscle force to P mvO2 increased. In conclusion, reduction of hemoglobin-oxygen affinity via RSR13 in AL increased P mvO2 and improved muscle contractile performance most likely via enhanced blood-muscle O2 diffusion. NEW & NOTEWORTHY This is the first investigation to examine the effect of RSR13 (erythrocyte allosteric effector) on skeletal muscle microvascular oxygen partial pressure kinetics and contractile function using an arterial ligation model of peripheral arterial disease in experimental animals. The present results provide strong support for the concept that reducing hemoglobin-O2 affinity via RSR13 improved tibialis anterior muscle contractile performance most likely via enhanced blood-muscle O2 diffusion.
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Affiliation(s)
- Aiko Watanabe
- Department of Engineering Science, University of Electro-Communications, Chofu, Tokyo, Japan; and
| | - David C. Poole
- Departments of Anatomy, Physiology and Kinesiology, Kansas State University, Manhattan, KS
| | - Yutaka Kano
- Department of Engineering Science, University of Electro-Communications, Chofu, Tokyo, Japan; and
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Dovlo E, Lashkari B, Soo Sean Choi S, Mandelis A, Shi W, Liu FF. Quantitative phase-filtered wavelength-modulated differential photoacoustic radar tumor hypoxia imaging toward early cancer detection. JOURNAL OF BIOPHOTONICS 2017; 10:1134-1142. [PMID: 27758051 DOI: 10.1002/jbio.201600168] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 08/21/2016] [Accepted: 09/28/2016] [Indexed: 06/06/2023]
Abstract
Overcoming the limitations of conventional linear spectroscopy used in multispectral photoacoustic imaging, wherein a linear relationship is assumed between the absorbed optical energy and the absorption spectra of the chromophore at a specific location, is crucial for obtaining accurate spatially-resolved quantitative functional information by exploiting known chromophore-specific spectral characteristics. This study introduces a non-invasive phase-filtered differential photoacoustic technique, wavelength-modulated differential photoacoustic radar (WM-DPAR) imaging that addresses this issue by eliminating the effect of the unknown wavelength-dependent fluence. It employs two laser wavelengths modulated out-of-phase to significantly suppress background absorption while amplifying the difference between the two photoacoustic signals. This facilitates pre-malignant tumor identification and hypoxia monitoring, as minute changes in total hemoglobin concentration and hemoglobin oxygenation are detectable. The system can be tuned for specific applications such as cancer screening and SO2 quantification by regulating the amplitude ratio and phase shift of the signal. The WM-DPAR imaging of a head and neck carcinoma tumor grown in the thigh of a nude rat demonstrates the functional PA imaging of small animals in vivo. The PA appearance of the tumor in relation to tumor vascularity is investigated by immunohistochemistry. Phase-filtered WM-DPAR imaging is also illustrated, maximizing quantitative SO2 imaging fidelity of tissues. Oxygenation levels within a tumor grown in the thigh of a nude rat using the two-wavelength phase-filtered differential PAR method.
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Affiliation(s)
- Edem Dovlo
- Center for Advanced Diffusion-Wave and Photoacoustic Technologies (CADIPT), Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON, M5S 3G8, Canada
| | - Bahman Lashkari
- Center for Advanced Diffusion-Wave and Photoacoustic Technologies (CADIPT), Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON, M5S 3G8, Canada
| | - Sung Soo Sean Choi
- Center for Advanced Diffusion-Wave and Photoacoustic Technologies (CADIPT), Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON, M5S 3G8, Canada
| | - Andreas Mandelis
- Center for Advanced Diffusion-Wave and Photoacoustic Technologies (CADIPT), Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON, M5S 3G8, Canada
| | - Wei Shi
- Ontario Cancer Institute, Princess Margaret Hospital, 610 University Ave, Toronto, ON, M5G 2M9, Canada
| | - Fei-Fei Liu
- Ontario Cancer Institute, Princess Margaret Hospital, 610 University Ave, Toronto, ON, M5G 2M9, Canada
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Vascular K ATP channels mitigate severe muscle O 2 delivery-utilization mismatch during contractions in chronic heart failure rats. Respir Physiol Neurobiol 2017; 238:33-40. [PMID: 28119150 DOI: 10.1016/j.resp.2017.01.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 01/10/2017] [Accepted: 01/18/2017] [Indexed: 12/14/2022]
Abstract
The vascular ATP-sensitive K+ (KATP) channel is a mediator of skeletal muscle microvascular oxygenation (PO2mv) during contractions in health. We tested the hypothesis that KATP channel function is preserved in chronic heart failure (CHF) and therefore its inhibition would reduce PO2mv and exacerbate the time taken to reach the PO2mv steady-state during contractions of the spinotrapezius muscle. Moreover, we hypothesized that subsequent KATP channel activation would oppose the effects of this inhibition. Muscle PO2mv (phosphorescence quenching) was measured during 180s of 1-Hz twitch contractions (∼6V) under control, glibenclamide (GLI, KATP channel antagonist; 5mg/kg) and pinacidil (PIN, KATP channel agonist; 5mg/kg) conditions in 16 male Sprague-Dawley rats with CHF induced via myocardial infarction (coronary artery ligation, left ventricular end-diastolic pressure: 18±1mmHg). GLI reduced baseline PO2mv (control: 28.3±0.9, GLI: 24.8±1.0mmHg, p<0.05), lowered mean PO2mv (average PO2mv during the overall time taken to reach the steady-state; control: 20.6±0.6, GLI: 17.6±0.3mmHg, p<0.05), and slowed the attainment of steady-state PO2mv (overall mean response time; control: 66.1±10.2, GLI: 93.6±7.8s, p<0.05). PIN opposed these effects on the baseline PO2mv, mean PO2mv and time to reach the steady-state PO2mv (p<0.05 for all vs. GLI). Inhibition of KATP channels exacerbates the transient mismatch between muscle O2 delivery and utilization in CHF rats and this effect is opposed by PIN. These data reveal that the KATP channel constitutes one of the select few well-preserved mechanisms of skeletal muscle microvascular oxygenation control in CHF.
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Hirai DM, Zelt JT, Jones JH, Castanhas LG, Bentley RF, Earle W, Staples P, Tschakovsky ME, McCans J, O’Donnell DE, Neder JA. Dietary nitrate supplementation and exercise tolerance in patients with heart failure with reduced ejection fraction. Am J Physiol Regul Integr Comp Physiol 2017; 312:R13-R22. [DOI: 10.1152/ajpregu.00263.2016] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 10/03/2016] [Accepted: 10/26/2016] [Indexed: 11/22/2022]
Abstract
Endothelial dysfunction and reduced nitric oxide (NO) signaling are key abnormalities leading to skeletal muscle oxygen delivery-utilization mismatch and poor physical capacity in patients with heart failure with reduced ejection fraction (HFrEF). Oral inorganic nitrate supplementation provides an exogenous source of NO that may enhance locomotor muscle function and oxygenation with consequent improvement in exercise tolerance in HFrEF. Thirteen patients (left ventricular ejection fraction ≤40%) were enrolled in a double-blind, randomized crossover study to receive concentrated nitrate-rich (nitrate) or nitrate-depleted (placebo) beetroot juice for 9 days. Low- and high-intensity constant-load cardiopulmonary exercise tests were performed with noninvasive measurements of central hemodynamics (stroke volume, heart rate, and cardiac output via impedance cardiography), arterial blood pressure, pulmonary oxygen uptake, quadriceps muscle oxygenation (near-infrared spectroscopy), and blood lactate concentration. Ten patients completed the study with no adverse clinical effects. Nitrate-rich supplementation resulted in significantly higher plasma nitrite concentration compared with placebo (240 ± 48 vs. 56 ± 8 nM, respectively; P < 0.05). There was no significant difference in the primary outcome of time to exercise intolerance between nitrate and placebo (495 ± 53 vs. 489 ± 58 s, respectively; P > 0.05). Similarly, there were no significant differences in central hemodynamics, arterial blood pressure, pulmonary oxygen uptake kinetics, skeletal muscle oxygenation, or blood lactate concentration from rest to low- or high-intensity exercise between conditions. Oral inorganic nitrate supplementation with concentrated beetroot juice did not present with beneficial effects on central or peripheral components of the oxygen transport pathway thereby failing to improve exercise tolerance in patients with moderate HFrEF.
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Affiliation(s)
- Daniel M. Hirai
- Department of Medicine, Division of Respirology, Laboratory of Clinical Exercise Physiology, Queen’s University, Kingston, Ontario, Canada
- Department of Medicine, Respiratory Division, Pulmonary Function and Clinical Exercise Physiology Unit, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Joel T. Zelt
- Department of Medicine, Division of Respirology, Laboratory of Clinical Exercise Physiology, Queen’s University, Kingston, Ontario, Canada
| | - Joshua H. Jones
- Department of Medicine, Division of Respirology, Laboratory of Clinical Exercise Physiology, Queen’s University, Kingston, Ontario, Canada
| | - Luiza G. Castanhas
- Department of Medicine, Division of Respirology, Laboratory of Clinical Exercise Physiology, Queen’s University, Kingston, Ontario, Canada
| | - Robert F. Bentley
- School of Kinesiology and Health Studies, Human Vascular Control Laboratory, Queen’s University, Kingston, Ontario, Canada
| | - Wendy Earle
- Department of Medicine, Division of Cardiology, Queen’s University, Kingston, Ontario, Canada; and
| | - Patti Staples
- Department of Medicine, Division of Cardiology, Queen’s University, Kingston, Ontario, Canada; and
| | - Michael E. Tschakovsky
- School of Kinesiology and Health Studies, Human Vascular Control Laboratory, Queen’s University, Kingston, Ontario, Canada
| | - John McCans
- Department of Medicine, Division of Cardiology, Queen’s University, Kingston, Ontario, Canada; and
| | - Denis E. O’Donnell
- Department of Medicine, Division of Respirology, Respiratory Investigation Unit, Queen’s University, Kingston, Ontario, Canada
| | - J. Alberto Neder
- Department of Medicine, Division of Respirology, Laboratory of Clinical Exercise Physiology, Queen’s University, Kingston, Ontario, Canada
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Niemeijer VM, Spee RF, Schoots T, Wijn PFF, Kemps HMC. Limitations of skeletal muscle oxygen delivery and utilization during moderate-intensity exercise in moderately impaired patients with chronic heart failure. Am J Physiol Heart Circ Physiol 2016; 311:H1530-H1539. [DOI: 10.1152/ajpheart.00474.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 09/28/2016] [Indexed: 11/22/2022]
Abstract
The extent and speed of transient skeletal muscle deoxygenation during exercise onset in patients with chronic heart failure (CHF) are related to impairments of local O2 delivery and utilization. This study examined the physiological background of submaximal exercise performance in 19 moderately impaired patients with CHF (Weber class A, B, and C) compared with 19 matched healthy control (HC) subjects by measuring skeletal muscle oxygenation (SmO2) changes during cycling exercise. All subjects performed two subsequent moderate-intensity 6-min exercise tests (bouts 1 and 2) with measurements of pulmonary oxygen uptake kinetics and SmO2 using near-infrared spatially resolved spectroscopy at the vastus lateralis for determination of absolute oxygenation values, amplitudes, kinetics (mean response time for onset), and deoxygenation overshoot characteristics. In CHF, deoxygenation kinetics were slower compared with HC (21.3 ± 5.3 s vs. 16.7 ± 4.4 s, P < 0.05, respectively). After priming exercise (i.e., during bout 2), deoxygenation kinetics were accelerated in CHF to values no longer different from HC (16.9 ± 4.6 s vs. 15.4 ± 4.2 s, P = 0.35). However, priming did not speed deoxygenation kinetics in CHF subjects with a deoxygenation overshoot, whereas it did reduce the incidence of the overshoot in this specific group ( P < 0.05). These results provide evidence for heterogeneity with respect to limitations of O2 delivery and utilization during moderate-intensity exercise in patients with CHF, with slowed deoxygenation kinetics indicating a predominant O2 utilization impairment and the presence of a deoxygenation overshoot, with a reduction after priming in a subgroup, indicating an initial O2 delivery to utilization mismatch.
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Affiliation(s)
- Victor M. Niemeijer
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven, the Netherlands; and
| | - Ruud F. Spee
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
| | - Thijs Schoots
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
| | - Pieter F. F. Wijn
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven, the Netherlands; and
- Department of Medical Physics, Máxima Medical Centre, Veldhoven, the Netherlands
| | - Hareld M. C. Kemps
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
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24
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Colburn TD, Ferguson SK, Holdsworth CT, Craig JC, Musch TI, Poole DC. Effect of sodium nitrite on local control of contracting skeletal muscle microvascular oxygen pressure in healthy rats. J Appl Physiol (1985) 2016; 122:153-160. [PMID: 27789769 DOI: 10.1152/japplphysiol.00367.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 10/13/2016] [Accepted: 10/20/2016] [Indexed: 12/21/2022] Open
Abstract
Exercise intolerance characteristic of diseases such as chronic heart failure (CHF) and diabetes is associated with reduced nitric oxide (NO) bioavailability from nitric oxide synthase (NOS), resulting in an impaired microvascular O2 driving pressure (Po2mv; O2 delivery/O2 utilization) and metabolic control. Infusions of the potent NO donor sodium nitroprusside augment NO bioavailability yet decrease mean arterial pressure (MAP) thereby reducing its potential efficacy for patient populations. To eliminate or reduce hypotensive sequelae, [Formula: see text] was superfused onto the spinotrapezius muscle. It was hypothesized that local [Formula: see text] administration would elevate resting Po2mv and slow Po2mv kinetics [increased time constant (τ) and mean response time (MRT)] following the onset of muscle contractions without decreasing MAP. In 12 anesthetized male Sprague-Dawley rats, Po2mv of the circulation-intact spinotrapezius muscle was measured by phosphorescence quenching during 180 s of electrically induced twitch contractions (1 Hz) before and after superfusion of sodium nitrite (NaNO2 30 mM). [Formula: see text] superfusion elevated resting Po2mv (control: 28.4 ± 1.1 vs. [Formula: see text]: 31.6 ± 1.2 mmHg; P ≤ 0.05), τ (control: 12.3 ± 1.2 vs. [Formula: see text]: 19.7 ± 2.2 s; P ≤ 0.05), and MRT (control: 19.3 ± 1.9 vs. [Formula: see text]: 25.6 ± 3.3 s; P ≤ 0.05). Importantly, these effects occurred in the absence of any reduction in MAP (103 ± 4 vs. 105 ± 4 mmHg, pre- and postsuperfusion respectively; P > 0.05). These results indicate that [Formula: see text] supplementation delivered to the muscle directly through [Formula: see text] superfusion enhances the blood-myocyte oxygen driving pressure without compromising MAP at rest and following the onset of muscle contraction. This strategy has substantial clinical utility for a range of ischemic conditions. NEW & NOTEWORTHY Ischemic conditions as diverse as chronic heart failure (CHF) and frostbite inflict tissue damage via inadequate O2 delivery. Herein we demonstrate that direct application of sodium nitrite enhances the O2 supply-O2 demand relationship, raising microvascular O2 pressure in healthy skeletal muscle. This therapeutic action of nitrite-derived nitric oxide occurred without inducing systemic hypotension and has the potential to relieve focal ischemia and preserve tissue vitality by enhancing O2 delivery.
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Affiliation(s)
- Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, Kansas; and
| | - Scott K Ferguson
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Clark T Holdsworth
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Jesse C Craig
- Department of Kinesiology, Kansas State University, Manhattan, Kansas; and
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, Kansas; and.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, Kansas; and .,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
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Ferguson SK, Holdsworth CT, Colburn TD, Wright JL, Craig JC, Fees A, Jones AM, Allen JD, Musch TI, Poole DC. Dietary nitrate supplementation: impact on skeletal muscle vascular control in exercising rats with chronic heart failure. J Appl Physiol (1985) 2016; 121:661-9. [PMID: 27445296 DOI: 10.1152/japplphysiol.00014.2016] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 07/15/2016] [Indexed: 01/14/2023] Open
Abstract
Chronic heart failure (CHF) results in central and peripheral derangements that ultimately reduce skeletal muscle O2 delivery and impair exercise tolerance. Dietary nitrate (NO3 (-)) supplementation improves skeletal muscle vascular function and tolerance to exercise. We tested the hypothesis that NO3 (-) supplementation would elevate exercising skeletal muscle blood flow (BF) and vascular conductance (VC) in CHF rats. Myocardial infarction (MI) was induced (coronary artery ligation) in young adult male rats. After 21 days of recovery, rats randomly received 5 days of NO3 (-)-rich beetroot juice (CHF + BR, n = 10) or a placebo (CHF, n = 10). Mean arterial pressure (carotid artery catheter) and skeletal muscle BF (radiolabeled microspheres) were measured during treadmill exercise (20 m/min, 5% grade). CHF-induced dysfunction, as determined by myocardial infarction size (29 ± 3% and 33 ± 4% in CHF and CHF + BR, respectively) and left ventricular end-diastolic pressure (18 ± 2 and 18 ± 2 mmHg in CHF and CHF + BR, respectively), and exercising mean arterial pressure (131 ± 3 and 128 ± 4 mmHg in CHF and CHF + BR, respectively) were not different (P > 0.05) between groups. Total exercising hindlimb skeletal muscle BF (95 ± 5 and 116 ± 9 ml·min(-1)·100 g(-1) in CHF and CHF + BR, respectively) and VC (0.75 ± 0.05 and 0.90 ± 0.05 ml·min(-1)·100 g(-1)·mmHg(-1) in CHF and CHF + BR, respectively) were 22% and 20% greater in BR-supplemented rats, respectively (P < 0.05). During exercise, BF in 9 and VC in 10 hindlimb muscles and muscle portions were significantly greater in the CHF + BR group. These results provide strong evidence that dietary NO3 (-) supplementation improves skeletal muscle vascular function during exercise in rats with CHF and, thus, support the use of BR as a novel therapeutic modality for the treatment of CHF.
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Affiliation(s)
- Scott K Ferguson
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; Cardiovascular and Pulmonary Research Laboratory, Department of Medicine, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Clark T Holdsworth
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Jennifer L Wright
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Jesse C Craig
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Alex Fees
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Andrew M Jones
- Sport and Health Sciences, University of Exeter, St. Luke's Campus, Exeter, United Kingdom; and
| | - Jason D Allen
- Institute of Sport Exercise and Active Living, Victoria University, Melbourne, Victoria, Australia
| | - Timothy I Musch
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - David C Poole
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; Department of Kinesiology, Kansas State University, Manhattan, Kansas
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26
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Hirai DM, Musch TI, Poole DC. Exercise training in chronic heart failure: improving skeletal muscle O2 transport and utilization. Am J Physiol Heart Circ Physiol 2015; 309:H1419-39. [PMID: 26320036 DOI: 10.1152/ajpheart.00469.2015] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 08/23/2015] [Indexed: 01/13/2023]
Abstract
Chronic heart failure (CHF) impairs critical structural and functional components of the O2 transport pathway resulting in exercise intolerance and, consequently, reduced quality of life. In contrast, exercise training is capable of combating many of the CHF-induced impairments and enhancing the matching between skeletal muscle O2 delivery and utilization (Q̇mO2 and V̇mO2 , respectively). The Q̇mO2 /V̇mO2 ratio determines the microvascular O2 partial pressure (PmvO2 ), which represents the ultimate force driving blood-myocyte O2 flux (see Fig. 1). Improvements in perfusive and diffusive O2 conductances are essential to support faster rates of oxidative phosphorylation (reflected as faster V̇mO2 kinetics during transitions in metabolic demand) and reduce the reliance on anaerobic glycolysis and utilization of finite energy sources (thus lowering the magnitude of the O2 deficit) in trained CHF muscle. These adaptations contribute to attenuated muscle metabolic perturbations (e.g., changes in [PCr], [Cr], [ADP], and pH) and improved physical capacity (i.e., elevated critical power and maximal V̇mO2 ). Preservation of such plasticity in response to exercise training is crucial considering the dominant role of skeletal muscle dysfunction in the pathophysiology and increased morbidity/mortality of the CHF patient. This brief review focuses on the mechanistic bases for improved Q̇mO2 /V̇mO2 matching (and enhanced PmvO2 ) with exercise training in CHF with both preserved and reduced ejection fraction (HFpEF and HFrEF, respectively). Specifically, O2 convection within the skeletal muscle microcirculation, O2 diffusion from the red blood cell to the mitochondria, and muscle metabolic control are particularly susceptive to exercise training adaptations in CHF. Alternatives to traditional whole body endurance exercise training programs such as small muscle mass and inspiratory muscle training, pharmacological treatment (e.g., sildenafil and pentoxifylline), and dietary nitrate supplementation are also presented in light of their therapeutic potential. Adaptations within the skeletal muscle O2 transport and utilization system underlie improvements in physical capacity and quality of life in CHF and thus take center stage in the therapeutic management of these patients.
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Affiliation(s)
- Daniel M Hirai
- Department of Medicine, Queen's University, Kingston, Ontario, Canada; Department of Medicine, Federal University of São Paulo (UNIFESP), São Paulo, São Paulo, Brazil; and
| | - Timothy I Musch
- Departments of Anatomy and Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
| | - David C Poole
- Departments of Anatomy and Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
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27
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Eshima H, Poole DC, Kano Y. In vivo Ca2+ buffering capacity and microvascular oxygen pressures following muscle contractions in diabetic rat skeletal muscles: fiber-type specific effects. Am J Physiol Regul Integr Comp Physiol 2015; 309:R128-37. [DOI: 10.1152/ajpregu.00044.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 05/01/2015] [Indexed: 11/22/2022]
Abstract
In Type 1 diabetes, skeletal muscle resting intracellular Ca2+ concentration ([Ca2+]i) homeostasis is impaired following muscle contractions. It is unclear to what degree this behavior is contingent upon fiber type and muscle oxygenation conditions. We tested the hypotheses that: 1) the rise in resting [Ca2+]i evident in diabetic rat slow-twitch (type I) muscle would be exacerbated in fast-twitch (type II) muscle following contraction; and 2) these elevated [Ca2+]i levels would relate to derangement of microvascular partial pressure of oxygen (PmvO2) rather than sarcoplasmic reticulum dysfunction per se. Adult male Wistar rats were divided randomly into diabetic (DIA: streptozotocin ip) and healthy (CONT) groups. Four weeks later extensor digitorum longus (EDL, predominately type II fibers) and soleus (SOL, predominately type I fibers) muscle contractions were elicited by continuous electrical stimulation (120 s, 100 Hz). Ca2+ imaging was achieved using fura 2-AM in vivo (i.e., circulation intact). DIA increased fatigability in EDL ( P < 0.05) but not SOL. In recovery, SOL [Ca2+]i either returned to its resting baseline within 150 s (CONT 1.00 ± 0.02 at 600 s) or was not elevated in recovery at all (DIA 1.03 ± 0.02 at 600 s, P > 0.05). In recovery, EDL CONT [Ca2+]i also decreased to values not different from baseline (1.06 ± 0.01, P > 0.05) at 600 s. In marked contrast, EDL DIA [Ca2+]i remained elevated for the entire recovery period (i.e., 1.23 ± 0.03 at 600 s, P < 0.05). The inability of [Ca2+]i to return to baseline in EDL DIA was not associated with any reduction of SR Ca2+-ATPase (SERCA) 1 or SERCA2 protein levels (both increased 30–40%, P < 0.05). However, PmvO2 recovery kinetics were markedly slowed in EDL such that mean PmvO2 was substantially depressed (CONT 27.9 ± 2.0 vs. DIA 18.4 ± 2.0 Torr, P < 0.05), and this behavior was associated with the elevated [Ca2+]i. In contrast, this was not the case for SOL ( P > 0.05) in that neither [Ca2+]i nor PmvO2 were deranged in recovery with DIA. In conclusion, recovery of [Ca2+]i homeostasis is impaired in diabetic rat fast-twitch but not slow-twitch muscle in concert with reduced PmvO2 pressures.
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Affiliation(s)
- Hiroaki Eshima
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Tokyo, Japan; and
| | - David C. Poole
- Departments of Anatomy & Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Yutaka Kano
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Tokyo, Japan; and
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28
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Niemeijer VM, Spee RF, Jansen JP, Buskermolen ABC, van Dijk T, Wijn PFF, Kemps HMC. Test-retest reliability of skeletal muscle oxygenation measurements during submaximal cycling exercise in patients with chronic heart failure. Clin Physiol Funct Imaging 2015; 37:68-78. [DOI: 10.1111/cpf.12269] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 04/27/2015] [Indexed: 01/26/2023]
Affiliation(s)
| | - Ruud F. Spee
- Department of Cardiology; Máxima Medical Centre; Veldhoven The Netherlands
| | - Jasper P. Jansen
- Department of Biomedical Engineering; Eindhoven University of Technology; Eindhoven The Netherlands
| | | | - Thomas van Dijk
- Department of Medical Physics; Máxima Medical Centre; Veldhoven The Netherlands
| | - Pieter F. F. Wijn
- Department of Applied Physics; Eindhoven University of Technology; Eindhoven The Netherlands
- Department of Medical Physics; Máxima Medical Centre; Veldhoven The Netherlands
| | - Hareld M. C. Kemps
- Department of Cardiology; Máxima Medical Centre; Veldhoven The Netherlands
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29
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Characterization of exercise limitations by evaluating individual cardiac output patterns: a prospective cohort study in patients with chronic heart failure. BMC Cardiovasc Disord 2015; 15:57. [PMID: 26100151 PMCID: PMC4476170 DOI: 10.1186/s12872-015-0057-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Accepted: 06/12/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Patients with chronic heart failure (CHF) suffer from exercise intolerance due to impaired central hemodynamics and subsequent alterations in peripheral skeletal muscle function and structure. The relative contribution of central versus peripheral factors in the reduced exercise capacity is still subject of debate. The main purpose was to investigate heterogeneity in the nature of exercise intolerance by evaluating individual cardiac output (Q) patterns. The secondary purpose was to evaluate whether patient and disease characteristics were associated with a central hemodynamic exercise limitation. METHODS Sixty-four stable CHF patients performed a symptom limited incremental exercise test with respiratory gas analysis and simultaneous assessment of Q, using a radial artery pulse contour analysis method. A central hemodynamic exercise limitation was defined as a plateau or decline in Q from 90 to 100 % of exercise duration. RESULTS Data from 61 patients were analyzed. A central hemodynamic exercise limitation was observed in 21 patients (34 %). In these patients, a higher occurrence of a plateau/decrease in oxygen uptake (VO2) (52 % vs 23 %, p = 0.02), stroke volume (SV) (100 % vs. 75 %, p = 0.01) and chronotropic incompetence (31 % vs. 2.5 %, p = 0.01) was observed, while presence of a left bundle branch block (LBBB) occurred significantly less (19 % vs 48 %, p = 0.03) There was no difference in disease characteristics such as etiology, duration, NYHA class, mitral regurgitation or ischemia. CONCLUSIONS The study revealed considerable heterogeneity in the nature of exercise limitations between moderately impaired CHF patients. In one third of the study population a plateau or decrease in Q towards peak exercise was demonstrated, which is indicative of a central hemodynamic exercise limitation. A central hemodynamic exercise limitation was associated with an impairment to augment stroke volume and heart rate.
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30
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Oliveira MF, Zelt JTJ, Jones JH, Hirai DM, O'Donnell DE, Verges S, Neder JA. Does impaired O2 delivery during exercise accentuate central and peripheral fatigue in patients with coexistent COPD-CHF? Front Physiol 2015; 5:514. [PMID: 25610401 PMCID: PMC4285731 DOI: 10.3389/fphys.2014.00514] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 12/15/2014] [Indexed: 02/04/2023] Open
Abstract
Impairment in oxygen (O2) delivery to the central nervous system ("brain") and skeletal locomotor muscle during exercise has been associated with central and peripheral neuromuscular fatigue in healthy humans. From a clinical perspective, impaired tissue O2 transport is a key pathophysiological mechanism shared by cardiopulmonary diseases, such as chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF). In addition to arterial hypoxemic conditions in COPD, there is growing evidence that cerebral and muscle blood flow and oxygenation can be reduced during exercise in both isolated COPD and CHF. Compromised cardiac output due to impaired cardiopulmonary function/interactions and blood flow redistribution to the overloaded respiratory muscles (i.e., ↑work of breathing) may underpin these abnormalities. Unfortunately, COPD and CHF coexist in almost a third of elderly patients making these mechanisms potentially more relevant to exercise intolerance. In this context, it remains unknown whether decreased O2 delivery accentuates neuromuscular manifestations of central and peripheral fatigue in coexistent COPD-CHF. If this holds true, it is conceivable that delivering a low-density gas mixture (heliox) through non-invasive positive pressure ventilation could ameliorate cardiopulmonary function/interactions and reduce the work of breathing during exercise in these patients. The major consequence would be increased O2 delivery to the brain and active muscles with potential benefits to exercise capacity (i.e., ↓central and peripheral neuromuscular fatigue, respectively). We therefore hypothesize that patients with coexistent COPD-CHF stop exercising prematurely due to impaired central motor drive and muscle contractility as the cardiorespiratory system fails to deliver sufficient O2 to simultaneously attend the metabolic demands of the brain and the active limb muscles.
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Affiliation(s)
- Mayron F Oliveira
- Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, School of Medicine, Federal University of São Paulo (UNIFESP) São Paulo, Brazil
| | - Joel T J Zelt
- Laboratory of Clinical Exercise Physiology, Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University Kingston, ON, Canada
| | - Joshua H Jones
- Laboratory of Clinical Exercise Physiology, Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University Kingston, ON, Canada
| | - Daniel M Hirai
- Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, School of Medicine, Federal University of São Paulo (UNIFESP) São Paulo, Brazil ; Laboratory of Clinical Exercise Physiology, Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University Kingston, ON, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University Kingston, ON, Canada
| | - Samuel Verges
- HP2 Laboratory, Grenoble Alpes University Grenoble, France
| | - J Alberto Neder
- Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, School of Medicine, Federal University of São Paulo (UNIFESP) São Paulo, Brazil ; Laboratory of Clinical Exercise Physiology, Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University Kingston, ON, Canada
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Woodside JDS, Gutowski M, Fall L, James PE, McEneny J, Young IS, Ogoh S, Bailey DM. Systemic oxidative-nitrosative-inflammatory stress during acute exercise in hypoxia; implications for microvascular oxygenation and aerobic capacity. Exp Physiol 2014; 99:1648-62. [DOI: 10.1113/expphysiol.2014.081265] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- John D. S. Woodside
- Vascular Physiology Unit; Institute of Cardiovascular Science; University College London; London UK
| | - Mariusz Gutowski
- Institute of Biochemistry and Cell Biology; Shanghai Institute for Biological Sciences; Chinese Academy of Sciences; Shanghai China
| | - Lewis Fall
- Neurovascular Research Laboratory; Faculty of Life Sciences and Education; University of South Wales; Pontypridd UK
| | - Philip E. James
- Wales Heart Research Institute; Cardiff University School of Medicine; Heath Park Cardiff Pontypridd UK
| | - Jane McEneny
- Centre for Public Health; Nutrition and Metabolism Group; Queen's University Belfast; Belfast UK
| | - Ian S. Young
- Centre for Public Health; Nutrition and Metabolism Group; Queen's University Belfast; Belfast UK
| | - Shigehiko Ogoh
- Department of Biomedical Engineering; Toyo University; Kawagoe-Shi Saitama Japan
| | - Damian M. Bailey
- Neurovascular Research Laboratory; Faculty of Life Sciences and Education; University of South Wales; Pontypridd UK
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Kano Y, Miura S, Eshima H, Ezaki O, Poole DC. The effects of PGC-1α on control of microvascular Po2 kinetics following onset of muscle contractions. J Appl Physiol (1985) 2014; 117:163-70. [DOI: 10.1152/japplphysiol.00080.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
During contractions, regulation of microvascular oxygen partial pressure (Pmvo2), which drives blood-myocyte O2 flux, is a function of skeletal muscle fiber type and oxidative capacity and can be altered by exercise training. The kinetics of Pmvo2 during contractions in predominantly fast-twitch muscles evinces a more rapid fall to far lower levels compared with slow-twitch counterparts. Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) improves endurance performance, in part, due to mitochondrial biogenesis, a fiber-type switch to oxidative fibers, and angiogenesis in skeletal muscle. We tested the hypothesis that improvement of exercise capacity by genetic overexpression of PGC-1α would be associated with an altered Pmvo2 kinetics profile of the fast-twitch (white) gastrocnemius during contractions toward that seen in slow-twitch muscles (i.e., slowed response kinetics and elevated steady-state Pmvo2). Phosphorescence quenching techniques were used to measure Pmvo2 at rest and during separate bouts of twitch (1 Hz) and tetanic (100 Hz) contractions in gastrocnemius muscles of mice with overexpression of PGC-1α and wild-type littermates (WT) mice under isoflurane anesthesia. Muscles of PGC-1α mice exhibited less fatigue than WT ( P < 0.01). However, except for the Pmvo2 response immediately following onset of contractions, WT and PGC-1α mice demonstrated similar Pmvo2 kinetics. Specifically, the time delay of the Pmvo2 response was shortened in PGC-1α mice compared with WT (1 Hz: WT, 6.6 ± 2.4 s; PGC-1α, 2.9 ± 0.8 s; 100 Hz: WT, 3.3 ± 1.1 s, PGC-1α, 0.9 ± 0.3 s, both P < 0.05). The ratio of muscle force to Pmvo2 was higher for the duration of tetanic contractions in PGC-1α mice. Slower dynamics and maintenance of higher Pmvo2 following muscle contractions is not obligatory for improved fatigue resistance in fast-twitch muscle of PGC-1α mice. Moreover, overexpression of PGC-1α may accelerate O2 utilization kinetics to a greater extent than O2 delivery kinetics.
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Affiliation(s)
- Yutaka Kano
- Department of Engineering Science, University of Electro-Communications, Chofu, Tokyo, Japan
| | - Shinji Miura
- Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan
| | - Hiroaki Eshima
- Department of Engineering Science, University of Electro-Communications, Chofu, Tokyo, Japan
| | - Osamu Ezaki
- Department of Human Health and Design, Showa Women's University, Tokyo, Japan; and
| | - David C. Poole
- Departments of Anatomy, Physiology, and Kinesiology, Kansas State University, Manhattan, Kansas
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33
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Hirai DM, Copp SW, Holdsworth CT, Ferguson SK, McCullough DJ, Behnke BJ, Musch TI, Poole DC. Skeletal muscle microvascular oxygenation dynamics in heart failure: exercise training and nitric oxide-mediated function. Am J Physiol Heart Circ Physiol 2014; 306:H690-8. [PMID: 24414070 DOI: 10.1152/ajpheart.00901.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chronic heart failure (CHF) impairs nitric oxide (NO)-mediated regulation of skeletal muscle O2 delivery-utilization matching such that microvascular oxygenation falls faster (i.e., speeds PO2mv kinetics) during increases in metabolic demand. Conversely, exercise training improves (slows) muscle PO2mv kinetics following contractions onset in healthy young individuals via NO-dependent mechanisms. We tested the hypothesis that exercise training would improve contracting muscle microvascular oxygenation in CHF rats partly via improved NO-mediated function. CHF rats (left ventricular end-diastolic pressure = 17 ± 2 mmHg) were assigned to sedentary (n = 11) or progressive treadmill exercise training (n = 11; 5 days/wk, 6-8 wk, final workload of 60 min/day at 35 m/min; -14% grade downhill running) groups. PO2mv was measured via phosphorescence quenching in the spinotrapezius muscle at rest and during 1-Hz twitch contractions under control (Krebs-Henseleit solution), sodium nitroprusside (SNP; NO donor; 300 μM), and N(G)-nitro-l-arginine methyl ester (L-NAME, nonspecific NO synthase blockade; 1.5 mM) superfusion conditions. Exercise-trained CHF rats had greater peak oxygen uptake and spinotrapezius muscle citrate synthase activity than their sedentary counterparts (p < 0.05 for both). The overall speed of the PO2mv fall during contractions (mean response time; MRT) was slowed markedly in trained compared with sedentary CHF rats (sedentary: 20.8 ± 1.4, trained: 32.3 ± 3.0 s; p < 0.05), and the effect was not abolished by L-NAME (sedentary: 16.8 ± 1.5, trained: 31.0 ± 3.4 s; p > 0.05). Relative to control, SNP increased MRT in both groups such that trained CHF rats had slower kinetics (sedentary: 43.0 ± 6.8, trained: 55.5 ± 7.8 s; p < 0.05). Improved NO-mediated function is not obligatory for training-induced improvements in skeletal muscle microvascular oxygenation (slowed PO2mv kinetics) following contractions onset in rats with CHF.
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Affiliation(s)
- Daniel M Hirai
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
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Abstract
Muscular exercise requires transitions to and from metabolic rates often exceeding an order of magnitude above resting and places prodigious demands on the oxidative machinery and O2-transport pathway. The science of kinetics seeks to characterize the dynamic profiles of the respiratory, cardiovascular, and muscular systems and their integration to resolve the essential control mechanisms of muscle energetics and oxidative function: a goal not feasible using the steady-state response. Essential features of the O2 uptake (VO2) kinetics response are highly conserved across the animal kingdom. For a given metabolic demand, fast VO2 kinetics mandates a smaller O2 deficit, less substrate-level phosphorylation and high exercise tolerance. By the same token, slow VO2 kinetics incurs a high O2 deficit, presents a greater challenge to homeostasis and presages poor exercise tolerance. Compelling evidence supports that, in healthy individuals walking, running, or cycling upright, VO2 kinetics control resides within the exercising muscle(s) and is therefore not dependent upon, or limited by, upstream O2-transport systems. However, disease, aging, and other imposed constraints may redistribute VO2 kinetics control more proximally within the O2-transport system. Greater understanding of VO2 kinetics control and, in particular, its relation to the plasticity of the O2-transport/utilization system is considered important for improving the human condition, not just in athletic populations, but crucially for patients suffering from pathologically slowed VO2 kinetics as well as the burgeoning elderly population.
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Affiliation(s)
- David C Poole
- Departments of Kinesiology, Anatomy, and Physiology, Kansas State University, Manhattan, Kansas, USA.
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Abstract
The activities of daily living typically occur at metabolic rates below the maximum rate of aerobic energy production. Such activity is characteristic of the nonsteady state, where energy demands, and consequential physiological responses, are in constant flux. The dynamics of the integrated physiological processes during these activities determine the degree to which exercise can be supported through rates of O₂ utilization and CO₂ clearance appropriate for their demands and, as such, provide a physiological framework for the notion of exercise intensity. The rate at which O₂ exchange responds to meet the changing energy demands of exercise--its kinetics--is dependent on the ability of the pulmonary, circulatory, and muscle bioenergetic systems to respond appropriately. Slow response kinetics in pulmonary O₂ uptake predispose toward a greater necessity for substrate-level energy supply, processes that are limited in their capacity, challenge system homeostasis and hence contribute to exercise intolerance. This review provides a physiological systems perspective of pulmonary gas exchange kinetics: from an integrative view on the control of muscle oxygen consumption kinetics to the dissociation of cellular respiration from its pulmonary expression by the circulatory dynamics and the gas capacitance of the lungs, blood, and tissues. The intensity dependence of gas exchange kinetics is discussed in relation to constant, intermittent, and ramped work rate changes. The influence of heterogeneity in the kinetic matching of O₂ delivery to utilization is presented in reference to exercise tolerance in endurance-trained athletes, the elderly, and patients with chronic heart or lung disease.
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Affiliation(s)
- Harry B Rossiter
- Institute of Membrane and Systems Biology, University of Leeds, Leeds, United Kingdom.
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36
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Bowen TS, Rossiter HB, Benson AP, Amano T, Kondo N, Kowalchuk JM, Koga S. Slowed oxygen uptake kinetics in hypoxia correlate with the transient peak and reduced spatial distribution of absolute skeletal muscle deoxygenation. Exp Physiol 2013; 98:1585-96. [DOI: 10.1113/expphysiol.2013.073270] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Spires J, Gladden LB, Grassi B, Goodwin ML, Saidel GM, Lai N. Distinguishing the effects of convective and diffusive O₂ delivery on VO₂ on-kinetics in skeletal muscle contracting at moderate intensity. Am J Physiol Regul Integr Comp Physiol 2013; 305:R512-21. [PMID: 23761640 DOI: 10.1152/ajpregu.00136.2013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
With current techniques, experimental measurements alone cannot characterize the effects of oxygen blood-tissue diffusion on muscle oxygen uptake (Vo₂) kinetics in contracting skeletal muscle. To complement experimental studies, a computational model is used to quantitatively distinguish the contributions of convective oxygen delivery, diffusion into cells, and oxygen utilization to Vo₂ kinetics. The model is validated using previously published experimental Vo₂ kinetics in response to slowed blood flow (Q) on-kinetics in canine muscle (τQ = 20 s, 46 s, and 64 s) [Goodwin ML, Hernández A, Lai N, Cabrera ME, Gladden LB. J Appl Physiol. 112:9-19, 2012]. Distinctive effects of permeability-surface area or diffusive conductance (PS) and Q on Vo₂ kinetics are investigated. Model simulations quantify the relationship between PS and Q, as well as the effects of diffusion associated with PS and Q dynamics on the mean response time of Vo₂. The model indicates that PS and Q are linearly related and that PS increases more with Q when convective delivery is limited by slower Q dynamics. Simulations predict that neither oxygen convective nor diffusive delivery are limiting Vo₂ kinetics in the isolated canine gastrocnemius preparation under normal spontaneous conditions during transitions from rest to moderate (submaximal) energy demand, although both operate close to the tipping point.
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Affiliation(s)
- Jessica Spires
- Departments of Biomedical Engineering, Case Western Reserve Univ., Cleveland, OH 44106-7207, USA
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Rehn TA, Munkvik M, Lunde PK, Sjaastad I, Sejersted OM. Intrinsic skeletal muscle alterations in chronic heart failure patients: a disease-specific myopathy or a result of deconditioning? Heart Fail Rev 2013; 17:421-36. [PMID: 21996779 DOI: 10.1007/s10741-011-9289-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Chronic heart failure (CHF) patients frequently experience impaired exercise tolerance due to skeletal muscle fatigue. Studies suggest that this in part is due to intrinsic alterations in skeletal muscle of CHF patients, often interpreted as a disease-specific myopathy. Knowledge about the mechanisms underlying these skeletal muscle alterations is of importance for the pathophysiological understanding of CHF, therapeutic approach and rehabilitation strategies. We here critically review the evidence for skeletal muscle alterations in CHF, the underlying mechanisms of such alterations and how skeletal muscle responds to training in this patient group. Skeletal muscle characteristics in CHF patients are very similar to what is reported in response to chronic obstructive pulmonary disease (COPD), detraining and deconditioning. Furthermore, skeletal muscle alterations observed in CHF patients are reversible by training, and skeletal muscle of CHF patients seems to be at least as trainable as that of matched controls. We argue that deconditioning is a major contributor to the skeletal muscle dysfunction in CHF patients and that further research is needed to determine whether, and to what extent, the intrinsic skeletal muscle alterations in CHF represent an integral part of the pathophysiology in this disease.
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Affiliation(s)
- T A Rehn
- Institute for Experimental Medical Research, Oslo University Hospital, Ullevaal, Oslo, Norway.
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Mechanical ventilation reduces rat diaphragm blood flow and impairs oxygen delivery and uptake. Crit Care Med 2012; 40:2858-66. [PMID: 22846782 DOI: 10.1097/ccm.0b013e31825b933a] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Although mechanical ventilation is a life-saving intervention in patients suffering from respiratory failure, prolonged mechanical ventilation is often associated with numerous complications including problematic weaning. In contracting skeletal muscle, inadequate oxygen supply can limit oxidative phosphorylation resulting in muscular fatigue. However, whether prolonged mechanical ventilation results in decreased diaphragmatic blood flow and induces an oxygen supply-demand imbalance in the diaphragm remains unknown. DESIGN We tested the hypothesis that prolonged controlled mechanical ventilation results in a time-dependent reduction in rat diaphragmatic blood flow and microvascular PO2 and that prolonged mechanical ventilation would diminish the diaphragm's ability to increase blood flow in response to muscular contractions. MEASUREMENTS AND MAIN RESULTS Compared to 30 mins of mechanical ventilation, 6 hrs of mechanical ventilation resulted in a 75% reduction in diaphragm blood flow (via radiolabeled microspheres), which did not occur in the intercostal muscle or high-oxidative hindlimb muscle (e.g., soleus). There was also a time-dependent decline in diaphragm microvascular PO2 (via phosphorescence quenching). Further, contrary to 30 mins of mechanical ventilation, 6 hrs of mechanical ventilation significantly compromised the diaphragm's ability to increase blood flow during electrically-induced contractions, which resulted in a ~80% reduction in diaphragm oxygen uptake. In contrast, 6 hrs of spontaneous breathing in anesthetized animals did not alter diaphragm blood flow or the ability to augment flow during electrically-induced contractions. CONCLUSIONS These new and important findings reveal that prolonged mechanical ventilation results in a time-dependent decrease in the ability of the diaphragm to augment blood flow to match oxygen demand in response to contractile activity and could be a key contributing factor to difficult weaning. Although additional experiments are required to confirm, it is tempting to speculate that this ventilator-induced decline in diaphragmatic oxygenation could promote a hypoxia-induced generation of reactive oxygen species in diaphragm muscle fibers and contribute to ventilator-induced diaphragmatic atrophy and contractile dysfunction.
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Sperandio PA, Oliveira MF, Rodrigues MK, Berton DC, Treptow E, Nery LE, Almeida DR, Neder JA. Sildenafil improves microvascular O2 delivery-to-utilization matching and accelerates exercise O2 uptake kinetics in chronic heart failure. Am J Physiol Heart Circ Physiol 2012; 303:H1474-80. [PMID: 23023868 DOI: 10.1152/ajpheart.00435.2012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) can temporally and spatially match microvascular oxygen (O(2)) delivery (Qo(2mv)) to O(2) uptake (Vo(2)) in the skeletal muscle, a crucial adjustment-to-exercise tolerance that is impaired in chronic heart failure (CHF). To investigate the effects of NO bioavailability induced by sildenafil intake on muscle Qo(2mv)-to-O(2) utilization matching and Vo(2) kinetics, 10 males with CHF (ejection fraction = 27 ± 6%) undertook constant work-rate exercise (70-80% peak). Breath-by-breath Vo(2), fractional O(2)extraction in the vastus lateralis {∼deoxygenated hemoglobin + myoglobin ([deoxy-Hb + Mb]) by near-infrared spectroscopy}, and cardiac output (CO) were evaluated after sildenafil (50 mg) or placebo. Sildenafil increased exercise tolerance compared with placebo by ∼20%, an effect that was related to faster on- and off-exercise Vo(2) kinetics (P < 0.05). Active treatment, however, failed to accelerate CO dynamics (P > 0.05). On-exercise [deoxy-Hb + Mb] kinetics were slowed by sildenafil (∼25%), and a subsequent response "overshoot" (n = 8) was significantly lessened or even abolished. In contrast, [deoxy-Hb + Mb] recovery was faster with sildenafil (∼15%). Improvements in muscle oxygenation with sildenafil were related to faster on-exercise Vo(2) kinetics, blunted oscillations in ventilation (n = 9), and greater exercise capacity (P < 0.05). Sildenafil intake enhanced intramuscular Qo(2mv)-to-Vo(2) matching with beneficial effects on Vo(2) kinetics and exercise tolerance in CHF. The lack of effect on CO suggests that improvement in blood flow to and within skeletal muscles underlies these effects.
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Affiliation(s)
- Priscila A Sperandio
- Pulmonary Function and Clinical Exercise Physiology Unit, Division of Respiratory Diseases, Department of Medicine, Federal University of São Paulo, Brazil
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Mezzani A, Grassi B, Jones AM, Giordano A, Corrà U, Porcelli S, Della Bella S, Taddeo A, Giannuzzi P. Speeding of pulmonary VO2 on-kinetics by light-to-moderate-intensity aerobic exercise training in chronic heart failure: clinical and pathophysiological correlates. Int J Cardiol 2012; 167:2189-95. [PMID: 22703939 DOI: 10.1016/j.ijcard.2012.05.124] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Revised: 05/09/2012] [Accepted: 05/28/2012] [Indexed: 12/11/2022]
Abstract
BACKGROUND Pulmonary VO2 on-kinetics during light-to-moderate-intensity constant-work-rate exercise, an experimental model mirroring energetic transitions during daily activities, has been shown to speed up with aerobic exercise training (AET) in normal subjects, but scant data are available in chronic heart failure (CHF). METHODS AND RESULTS Thirty CHF patients were randomized to 3 months of light-to-moderate-intensity AET (CHF-AET) or control (CHF-C). Baseline and end-protocol evaluations included i) one incremental cardiopulmonary exercise test with near infrared spectroscopy analysis of peak deoxygenated hemoglobin+myoglobin concentration changes (Δ[deoxy(Hb+Mb)]) in vastus lateralis muscle, ii) 8 light-to-moderate-intensity constant-work-rate exercise tests for VO2 on-kinetics phase I duration, phase II τ, and mean response time (MRT) assessment, and iii) circulating endothelial progenitor cell (EPC) measurement. Reference values were obtained in 7 age-matched normals (N). At end-protocol, phase I duration, phase II τ, and MRT were significantly reduced (-12%, -22%, and -19%, respectively) and peak VO2, peak Δ[deoxy(Hb+Mb)], and EPCs increased (9%, 20%, and 98%, respectively) in CHF-AET, but not in CHF-C. Peak Δ[deoxy(Hb+Mb)] and EPCs relative increase correlated significantly to that of peak VO2 (r=0.61 and 0.64, respectively, p<0.05). CONCLUSIONS Light-to-moderate-intensity AET determined a near-normalization of pulmonary VO2 on-kinetics in CHF patients. Such a marked plasticity has important implications for AET intensity prescription, especially in patients more functionally limited and with high exercise-related risk. The AET-induced simultaneous improvement of phase I and phase II, associated with an increase of peak peripheral oxygen extraction and EPCs, supports microcirculatory O2 delivery impairment as a key factor determining exercise intolerance in CHF.
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Affiliation(s)
- Alessandro Mezzani
- Exercise Pathophysiology Laboratory, Cardiac Rehabilitation Division, S Maugeri Foundation IRCCS, Scientific Institute of Veruno, Veruno, NO, Italy.
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Copp SW, Hirai DM, Ferguson SK, Holdsworth CT, Musch TI, Poole DC. Effects of chronic heart failure on neuronal nitric oxide synthase-mediated control of microvascular O2 pressure in contracting rat skeletal muscle. J Physiol 2012; 590:3585-96. [PMID: 22687613 DOI: 10.1113/jphysiol.2012.235929] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
UNLABELLED Chronic heart failure (CHF) impairs nitric oxide (NO)-mediated regulation of the skeletal muscle microvascular O(2) delivery/V(O(2)) ratio (which sets the microvascular O(2) pressure, PO(2)mv). Given the pervasiveness of endothelial dysfunction in CHF, this NO-mediated dysregulation is attributed generally to eNOS. It is unknown whether nNOS-mediated PO(2)mv regulation is altered in CHF. We tested the hypothesis that CHF impairs nNOS-mediated PO(2)mv control. In healthy and CHF (left ventricular end diastolic pressure (LVEDP): 6 ± 1 versus 14 ± 1 mmHg, respectively, P < 0.05) rats spinotrapezius muscle blood flow (radiolabelled microspheres), PO(2)mv (phosphorescence quenching), and V(O(2)) (Fick calculation) were measured before and after 0.56 mg kg(-1)i.a. of the selective nNOS inhibitor S-methyl-l-thiocitrulline (SMTC). In healthy rats, SMTC increased baseline PO(2)mv ( CONTROL 29.7 ± 1.4, SMTC: 34.4 ± 1.9 mmHg, P < 0.05) by reducing V(O(2)) (↓20%) without any effect on blood flow and speeded the mean response time (MRT, time to reach 63% of the overall kinetics response, CONTROL 24.2 ± 2.0, SMTC: 18.5 ± 1.3 s, P < 0.05). In CHF rats, SMTC did not alter baseline PO(2)mv ( CONTROL 25.7 ± 1.6, SMTC: 28.6 ± 2.1 mmHg, P > 0.05), V(O(2)) at rest, or the MRT (CONTROL: 22.8 ± 2.6, SMTC: 21.3 ± 3.0 s, P > 0.05). During the contracting steady-state, SMTC reduced blood flow (↓15%) and V(O(2)) (↓15%) in healthy rats such that PO(2)mv was unaltered ( CONTROL 19.8 ± 1.7, SMTC: 20.7 ± 1.8 mmHg, P > 0.05). In marked contrast, in CHF rats SMTC did not change contracting steady-state blood flow, V(O(2)), or PO(2)mv ( CONTROL 17.0 ± 1.4, SMTC: 17.7 ± 1.8 mmHg, P > 0.05). nNOS-mediated control of skeletal muscle microvascular function is compromised in CHF versus healthy rats. Treatments designed to ameliorate microvascular dysfunction in CHF may benefit by targeting improvements in nNOS function.
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Affiliation(s)
- Steven W Copp
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506-5802, USA
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Hirai DM, Copp SW, Ferguson SK, Holdsworth CT, McCullough DJ, Behnke BJ, Musch TI, Poole DC. Exercise training and muscle microvascular oxygenation: functional role of nitric oxide. J Appl Physiol (1985) 2012; 113:557-65. [PMID: 22678970 DOI: 10.1152/japplphysiol.00151.2012] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Exercise training induces multiple adaptations within skeletal muscle that may improve local O(2) delivery-utilization matching (i.e., Po(2)mv). We tested the hypothesis that increased nitric oxide (NO) function is intrinsic to improved muscle Po(2)mv kinetics from rest to contractions after exercise training. Healthy young Sprague-Dawley rats were assigned to sedentary (n = 18) or progressive treadmill exercise training (n = 10; 5 days/wk, 6-8 wk, final workload of 60 min/day at 35 m/min, -14% grade) groups. Po(2)mv was measured via phosphorescence quenching in the spinotrapezius muscle at rest and during 1-Hz twitch contractions under control (Krebs-Henseleit solution), sodium nitroprusside (SNP, NO donor; 300 μM), and N(G)-nitro-L-arginine methyl ester (l-NAME, nonspecific NO synthase blockade; 1.5 mM) superfusion conditions. Exercise-trained rats had greater peak oxygen uptake (Vo(2 peak)) than their sedentary counterparts (81 ± 1 vs. 72 ± 2 ml · kg(-1) · min(-1), respectively; P < 0.05). Exercise-trained rats had significantly slower Po(2)mv fall throughout contractions (τ(1); time constant for the first component) during control (sedentary: 8.1 ± 0.6; trained: 15.2 ± 2.8 s). Compared with control, SNP slowed τ(1) to a greater extent in sedentary rats (sedentary: 38.7 ± 5.6; trained: 26.8 ± 4.1 s; P > 0.05) whereas l-NAME abolished the differences in τ(1) between sedentary and trained rats (sedentary: 12.0 ± 1.7; trained: 11.2 ± 1.4 s; P < 0.05). Our results indicate that endurance exercise training leads to greater muscle microvascular oxygenation across the metabolic transient following the onset of contractions (i.e., slower Po(2)mv kinetics) partly via increased NO-mediated function, which likely constitutes an important mechanism for training-induced metabolic adaptations.
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Affiliation(s)
- Daniel M Hirai
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas 66506-5802, USA
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McDonough P, Padilla DJ, Kano Y, Musch TI, Poole DC, Behnke BJ. Plasticity of microvascular oxygenation control in rat fast-twitch muscle: effects of experimental creatine depletion. Respir Physiol Neurobiol 2012; 181:14-20. [PMID: 22285799 PMCID: PMC3296908 DOI: 10.1016/j.resp.2012.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2011] [Revised: 01/09/2012] [Accepted: 01/10/2012] [Indexed: 10/14/2022]
Abstract
Aging, heart failure and diabetes each compromise the matching of O2 delivery (Q˙O2)-to-metabolic requirements (O2 uptake, V˙O2) in skeletal muscle such that the O2 pressure driving blood-myocyte O2 flux (microvascular PO2, PmvO2) is reduced and contractile function impaired. In contrast, β-guanidinopropionic acid (β-GPA) treatment improves muscle contractile function, primarily in fast-twitch muscle (Moerland and Kushmerick, 1994). We tested the hypothesis that β-GPA (2% wt/BW in rat chow, 8 weeks; n=14) would improve Q˙O2-to-V˙O2 matching (elevated PmvO2) during contractions (4.5V @ 1Hz) in mixed (MG) and white (WG) portions of the gastrocnemius, both predominantly fast-twitch). Compared with control (CON), during contractions PmvO2 fell less following β-GPA (MG -54%, WG -26%, P<0.05), elevating steady-state PmvO2 (CON, MG: 10±2, WG: 9±1; β-GPA, MG 16±2, WG 18±2 mmHg, P<0.05). This reflected an increased Q˙O2/V˙O2 ratio due primarily to a reduced V˙O2 in β-GPA muscles. It is likely that this adaptation helps facilitate the β-GPA-induced enhancement of contractile function in fast-twitch muscles.
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Affiliation(s)
- Paul McDonough
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX 76019, USA
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Alveolar gas exchange and tissue deoxygenation during exercise in type 1 diabetes patients and healthy controls. Respir Physiol Neurobiol 2012; 181:267-76. [PMID: 22538274 DOI: 10.1016/j.resp.2012.04.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 03/16/2012] [Accepted: 04/06/2012] [Indexed: 11/22/2022]
Abstract
We used near-infrared spectroscopy to investigate whether leg and arm skeletal muscle and cerebral deoxygenation differ during incremental cycling exercise in men with type 1 diabetes (T1D, n=10, mean±SD age 33±7 years) and healthy control men (matched by age, anthrometry, and self-reported physical activity, CON, n=10, 32±7 years) to seek an explanation for lower aerobic capacity (˙VO2peak) often reported in T1D. T1D had lower ˙VO2peak (35±4mlkg(-1)min(-1) vs. 43±8mlkg(-1)min(-1), P<0.01) and peak work rate (219±33W vs. 290±44W, P<0.001) than CON. Leg muscle deoxygenation (↑ [deoxyhemoglobin]; ↓ tissue saturation index) was greater in T1D than CON at a given absolute submaximal work rate, but not at peak exercise, while arm muscle and cerebral deoxygenation were similar. Thus, in T1D compared with CON, faster leg muscle deoxygenation suggests limited circulatory ability to increase O(2) delivery as a plausible explanation for lower ˙VO2peak and earlier fatigue in T1D.
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Poole DC, Hirai DM, Copp SW, Musch TI. Muscle oxygen transport and utilization in heart failure: implications for exercise (in)tolerance. Am J Physiol Heart Circ Physiol 2012; 302:H1050-63. [PMID: 22101528 PMCID: PMC3311454 DOI: 10.1152/ajpheart.00943.2011] [Citation(s) in RCA: 206] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 11/17/2011] [Indexed: 01/01/2023]
Abstract
The defining characteristic of chronic heart failure (CHF) is an exercise intolerance that is inextricably linked to structural and functional aberrations in the O(2) transport pathway. CHF reduces muscle O(2) supply while simultaneously increasing O(2) demands. CHF severity varies from moderate to severe and is assessed commonly in terms of the maximum O(2) uptake, which relates closely to patient morbidity and mortality in CHF and forms the basis for Weber and colleagues' (167) classifications of heart failure, speed of the O(2) uptake kinetics following exercise onset and during recovery, and the capacity to perform submaximal exercise. As the heart fails, cardiovascular regulation shifts from controlling cardiac output as a means for supplying the oxidative energetic needs of exercising skeletal muscle and other organs to preventing catastrophic swings in blood pressure. This shift is mediated by a complex array of events that include altered reflex and humoral control of the circulation, required to prevent the skeletal muscle "sleeping giant" from outstripping the pathologically limited cardiac output and secondarily impacts lung (and respiratory muscle), vascular, and locomotory muscle function. Recently, interest has also focused on the dysregulation of inflammatory mediators including tumor necrosis factor-α and interleukin-1β as well as reactive oxygen species as mediators of systemic and muscle dysfunction. This brief review focuses on skeletal muscle to address the mechanistic bases for the reduced maximum O(2) uptake, slowed O(2) uptake kinetics, and exercise intolerance in CHF. Experimental evidence in humans and animal models of CHF unveils the microvascular cause(s) and consequences of the O(2) supply (decreased)/O(2) demand (increased) imbalance emblematic of CHF. Therapeutic strategies to improve muscle microvascular and oxidative function (e.g., exercise training and anti-inflammatory, antioxidant strategies, in particular) and hence patient exercise tolerance and quality of life are presented within their appropriate context of the O(2) transport pathway.
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Affiliation(s)
- David C Poole
- Departments of Anatomy and Physiology, and Kinesiology, Kansas State University, Manhattan, KS 66506-5802, USA.
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Koga S, Kano Y, Barstow TJ, Ferreira LF, Ohmae E, Sudo M, Poole DC. Kinetics of muscle deoxygenation and microvascular Po2 during contractions in rat: comparison of optical spectroscopy and phosphorescence-quenching techniques. J Appl Physiol (1985) 2012; 112:26-32. [DOI: 10.1152/japplphysiol.00925.2011] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The overarching presumption with near-infrared spectroscopy measurement of muscle deoxygenation is that the signal reflects predominantly the intramuscular microcirculatory compartment rather than intramyocyte myoglobin (Mb). To test this hypothesis, we compared the kinetics profile of muscle deoxygenation using visible light spectroscopy (suitable for the superficial fiber layers) with that for microvascular O2 partial pressure (i.e., PmvO2, phosphorescence quenching) within the same muscle region (0.5∼1 mm depth) during transitions from rest to electrically stimulated contractions in the gastrocnemius of male Wistar rats ( n = 14). Both responses could be modeled by a time delay (TD), followed by a close-to-exponential change to the new steady level. However, the TD for the muscle deoxygenation profile was significantly longer compared with that for the phosphorescence-quenching PmvO2 [8.6 ± 1.4 and 2.7 ± 0.6 s (means ± SE) for the deoxygenation and PmvO2, respectively; P < 0.05]. The time constants (τ) of the responses were not different (8.8 ± 4.7 and 11.2 ± 1.8 s for the deoxygenation and PmvO2, respectively). These disparate (TD) responses suggest that the deoxygenation characteristics of Mb extend the TD, thereby increasing the duration (number of contractions) before the onset of muscle deoxygenation. However, this effect was insufficient to increase the mean response time. Somewhat differently, the muscle deoxygenation response measured using near-infrared spectroscopy in the deeper regions (∼5 mm depth) (∼50% type I Mb-rich, highly oxidative fibers) was slower (τ = 42.3 ± 6.6 s; P < 0.05) than the corresponding value for superficial muscle measured using visible light spectroscopy or PmvO2 and can be explained on the basis of known fiber-type differences in PmvO2 kinetics. These data suggest that, within the superficial and also deeper muscle regions, the τ of the deoxygenation signal may represent a useful index of local O2 extraction kinetics during exercise transients.
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Affiliation(s)
- Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe
| | - Yutaka Kano
- The University of Electro-Communications, Chofu; and
| | - Thomas J. Barstow
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Leonardo F. Ferreira
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida; and
| | | | - Mizuki Sudo
- The University of Electro-Communications, Chofu; and
| | - David C. Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas
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Bowen TS, Cannon DT, Murgatroyd SR, Birch KM, Witte KK, Rossiter HB. The intramuscular contribution to the slow oxygen uptake kinetics during exercise in chronic heart failure is related to the severity of the condition. J Appl Physiol (1985) 2011; 112:378-87. [PMID: 22033530 DOI: 10.1152/japplphysiol.00779.2011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mechanism for slow pulmonary O(2) uptake (Vo(2)) kinetics in patients with chronic heart failure (CHF) is unclear but may be due to limitations in the intramuscular control of O(2) utilization or O(2) delivery. Recent evidence of a transient overshoot in microvascular deoxygenation supports the latter. Prior (or warm-up) exercise can increase O(2) delivery in healthy individuals. We therefore aimed to determine whether prior exercise could increase muscle oxygenation and speed Vo(2) kinetics during exercise in CHF. Fifteen men with CHF (New York Heart Association I-III) due to left ventricular systolic dysfunction performed two 6-min moderate-intensity exercise transitions (bouts 1 and 2, separated by 6 min of rest) from rest to 90% of lactate threshold on a cycle ergometer. Vo(2) was measured using a turbine and a mass spectrometer, and muscle tissue oxygenation index (TOI) was determined by near-infrared spectroscopy. Prior exercise increased resting TOI by 5.3 ± 2.4% (P = 0.001), attenuated the deoxygenation overshoot (-3.9 ± 3.6 vs. -2.0 ± 1.4%, P = 0.011), and speeded the Vo(2) time constant (τVo(2); 49 ± 19 vs. 41 ± 16 s, P = 0.003). Resting TOI was correlated to τVo(2) before (R(2) = 0.51, P = 0.014) and after (R(2) = 0.36, P = 0.051) warm-up exercise. However, the mean response time of TOI was speeded between bouts in half of the patients (26 ± 8 vs. 20 ± 8 s) and slowed in the remainder (32 ± 11 vs. 44 ± 16 s), the latter group having worse New York Heart Association scores (P = 0.042) and slower Vo(2) kinetics (P = 0.001). These data indicate that prior moderate-intensity exercise improves muscle oxygenation and speeds Vo(2) kinetics in CHF. The most severely limited patients, however, appear to have an intramuscular pathology that limits Vo(2) kinetics during moderate exercise.
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Affiliation(s)
- T Scott Bowen
- Institute of Membrane and Systems Biology, University of Leeds, Leeds, UK
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COPP STEVENW, HIRAI DANIELM, FERGUSON SCOTTK, MUSCH TIMOTHYI, POOLE DAVIDC. Role of Neuronal Nitric Oxide Synthase in Modulating Microvascular and Contractile Function in Rat Skeletal Muscle. Microcirculation 2011; 18:501-11. [DOI: 10.1111/j.1549-8719.2011.00111.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Oxygen uptake kinetics in chronic heart failure: clinical and physiological aspects. Neth Heart J 2011; 17:238-44. [PMID: 19789686 DOI: 10.1007/bf03086254] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
One of the hallmark symptoms of patients with chronic heart failure (CHF) is exercise intolerance. Therefore, exercise testing has become an important tool for the evaluation and monitoring of heart failure. Whereas the maximal aerobic capacity (peak VO(2)) is a reliable indicator of the severity and prognosis of heart failure, submaximal exercise parameters may be more closely related to the ability to perform daily activities. As such, oxygen (O(2)) uptake kinetics, describing the rate change of O(2) uptake during onset or recovery of submaximal constant-load exercise (O(2) onset and recovery kinetics, respectively), have been shown to be useful parameters for objectively evaluating the functional capacity of CHF patients. However, their evaluation in this population is not a routine part of daily clinical practice. Possible reasons for this include a lack of standardisation of the assessment methodology and a limited number of studies evaluating the clinical use of O(2) uptake kinetics in CHF patients. In addition, the pathophysiological mechanisms underlying the delay in O(2) uptake kinetics in these patients are not completely understood. This review discusses the current literature on the clinical potency and physiological determinants of O(2) uptake kinetics in CHF patients and provides directions for future research. (Neth Heart J 2009;17:238-44.Neth Heart J 2009;17:238-44.).
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