scholarly journals No relationship between progressive muscle hyperaemia and temperature in exercising rats

1989 ◽  
Vol 141 (1) ◽  
pp. 87-95
Author(s):  
M. D. Delp ◽  
M. H. Laughlin ◽  
R. B. Armstrong
Keyword(s):  
Blood Flow ◽  
Body Temperature ◽  
Gastrocnemius Muscle ◽  
Muscle Blood Flow ◽  
Submaximal Exercise ◽  
Miniature Swine ◽  
Hindlimb Muscle ◽  
Extensor Muscles ◽  
Exercise Muscle ◽  
Colonic Temperature

During prolonged submaximal exercise muscle blood flow has been shown to increase progressively in rats and miniature swine. This study was designed to test the hypothesis that the increases in muscle blood flow are associated with progressive elevations in body temperature in rats. Colonic temperature and muscle blood flow (determined using radioactive microspheres) were measured after 15, 30 and 45 min of exercise in rats exercising on a treadmill at 15 m min-1 on a 0 degree incline. Total hindlimb muscle blood flow increased from 79 +/− 8 ml min-1 100 g-1 at 15 min to 95 +/− 10 ml min-1 100 g-1 at 30 min (P less than 0.05). The greatest increases in blood flow occurred in the deep extensor muscles of the hindlimb. For example, in the red portion of the gastrocnemius muscle, blood flow increased from 197 +/− 15 ml min-1 100 g-1 at 15 min to 285 +/− 17 ml min-1 100 g-1 at 30 min (P less than 0.05). Colonic temperature, however, remained stable at 38.5 degrees C over this period. These data indicate that the progressive hyperaemia in muscle was unrelated to body temperature.

scholarly journals Rat hindlimb muscle blood flow during level and downhill locomotion

1999 ◽  
Vol 86 (2) ◽  
pp. 564-568 ◽  
Author(s):  
Michael D. Delp ◽  
Changping Duan ◽  
Chester A. Ray ◽  
R. B. Armstrong
Keyword(s):  
Blood Flow ◽  
Muscle Blood Flow ◽  
Muscle Metabolism ◽  
Whole Body ◽  
Flexor Muscle ◽  
Hindlimb Muscle ◽  
Downhill Exercise ◽  
Extensor Muscles ◽  
Flexor Muscles ◽  
Exercise Muscle

During eccentrically biased exercise (e.g., downhill locomotion), whole body oxygen consumption and blood lactate concentrations are lower than during level locomotion. These general systemic measurements indicate that muscle metabolism is lower during downhill exercise. This study was designed to test the hypothesis that hindlimb muscle blood flow is correspondingly lower during downhill vs. level exercise. Muscle blood flow (determined by using radioactive microspheres) was measured in rats after 15 min of treadmill exercise at 15 m/min on the level (L, 0°) or downhill (D, −17°). Blood flow to ankle extensor muscles was either lower (e.g., white gastrocnemius muscle: D, 9 ± 2; L, 15 ± 1 ml ⋅ min−1 ⋅ 100 g−1) or not different (e.g., soleus muscle: D, 250 ± 35; L, 230 ± 21 ml ⋅ min−1 ⋅ 100 g−1) in downhill vs. level exercise. In contrast, blood flow to ankle flexor muscles was higher (e.g., extensor digitorum longus muscle: D, 53 ± 5; L, 31 ± 6 ml ⋅ min−1 ⋅ 100 g−1) during downhill vs. level exercise. When individual extensor and flexor muscle flows were summed, total flow to the leg was lower during downhill exercise (D, 3.24 ± 0.08; L, 3.47 ± 0.05 ml/min). These data indicate that muscle blood flow and metabolism are lower during eccentrically biased exercise but are not uniformly reduced in all active muscles; i.e., flows are equivalent in several ankle extensor muscles and higher in ankle flexor muscles.

Plateau in muscle blood flow during prolonged exercise in miniature swine

1989 ◽  
Vol 66 (5) ◽  
pp. 2101-2108 ◽  
Author(s):  
M. D. McKirnan ◽  
C. G. Gray ◽  
F. C. White
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Prolonged Exercise ◽  
Regional Blood Flow ◽  
Muscle Blood Flow ◽  
Exercise Bout ◽  
Miniature Swine ◽  
Hindlimb Muscle ◽  
Exercise Period ◽  
Gastrointestinal Blood Flow

Cardiovascular, metabolic, and thermoregulatory responses were studied in eight male miniature swine during a prolonged treadmill run. Each animal underwent 8–10 wk of exercise training, thoracic surgery, and 3 wk of retraining before the experimental run. This regimen enabled the animals to run at 65% of the heart rate range (210–220 beats/min) for approximately 100 min. Skin wetting and a fan were used to cool the pigs during the run. Regional blood flow was significantly altered with the onset of exercise; however, hindlimb muscle and total gastrointestinal blood flow were unchanged throughout the exercise period. Compared with 5-min values, heart rate and cardiac output were significantly elevated by 17 beats/min and 31 ml.min-1.kg-1 at 60 min and by 20 beats/min and 33 ml.min-1.kg-1 at end exercise, respectively. Core temperatures increased between 5 and 30 min of exercise (39.4 vs. 39.9 degrees C) but then remained unchanged to the end of exercise. Mean arterial pressure, O2 consumption, and blood lactate did not change during the exercise bout. These data indicate that limiting increases in core temperature during prolonged exercise was associated with a plateau in active muscle blood flow.

Progressive elevations in muscle blood flow during prolonged exercise in swine

1987 ◽  
Vol 63 (1) ◽  
pp. 285-291 ◽  
Author(s):  
R. B. Armstrong ◽  
M. D. Delp ◽  
E. F. Goljan ◽  
M. H. Laughlin
Keyword(s):  
Blood Flow ◽  
Prolonged Exercise ◽  
Fiber Type ◽  
Muscle Blood Flow ◽  
Miniature Swine ◽  
Time Period ◽  
Type Composition ◽  
Muscle Groups ◽  
Colonic Temperature ◽  
Over Time

Distribution of muscle blood flow has not been measured in man during prolonged exercise, but progressive elevations in skin flow coupled with constant cardiac output (QT) have suggested muscle blood flow may be compromised. However, previous experiments with rats demonstrated progressive increases in muscle blood flow over time during prolonged submaximal exercise. The present study was performed to study muscle blood flow in miniature swine during long-term exercise to shed light on this apparent anomaly. QT and distribution of QT were studied with radiolabeled microspheres while pigs ran on a level treadmill at a speed (10.5 km/h) requiring 71 +/- 4% of maximal O2 consumption (VO2 max). QT increased 23% from the 5th to the 30th min of exercise, whereas total skeletal muscle flow increased by 49%. Increases in flow in the muscles resulted from decreased resistance, since mean arterial pressure declined over this time period (-7%). In addition, the proportional increases in muscle flow were similar within synergistic muscle groups independent of fiber type composition (e.g., elbow extensors: 59–78%; elbow flexors: 26–40%). The factor that limited continued exercise appeared to be body temperature. Colonic temperature rose in linear fashion over time; the animals became exhausted at approximately 42 degrees C. These flow data are similar to previous findings in rats and indicate that during prolonged treadmill locomotion in quadrupedal animals muscle blood flow increases over time to near maximal levels.

Sympathetic neural influences on muscle blood flow in rats during submaximal exercise

1988 ◽  
Vol 65 (1) ◽  
pp. 434-440 ◽  
Author(s):  
D. F. Peterson ◽  
R. B. Armstrong ◽  
M. H. Laughlin
Keyword(s):  
Blood Flow ◽  
Muscle Blood Flow ◽  
Sympathetic Innervation ◽  
Flow Distribution ◽  
Sympathetic Nerves ◽  
Submaximal Exercise ◽  
Fiber Types ◽  
Blood Flows ◽  
Hindlimb Muscles ◽  
Hindlimb Muscle

These experiments were designed to estimate the involvement of the sympathetic innervation in regulation of hindlimb muscle blood flow distribution among and within muscles during submaximal locomotory exercise in rats. Blood flows to 32 hindlimb muscles and 13 other selected tissues were measured using the radiolabeled microsphere technique, before exercise and at 0.5, 2, 5, and 15 min of treadmill exercise at 15 m/min. The two groups of rats studied were 1) intact control, and 2) acutely sympathectomized (hindlimb sympathectomy accomplished by bilateral section of the lumbar sympathetic chain and its connections to the spinal cord at L2-L3). There were no differences in total hindlimb muscle blood flow among the two groups during preexercise or at 30 s or 2 min of exercise. However, flow was higher in eight individual muscles at 2 min of exercise in the sympathectomized rats. At 5 and 15 min of exercise there was higher total hindlimb muscle blood flow in the denervated group compared with control. These differences were also present in many individual muscles. Our results suggest that 1) sympathetic nerves do not exert a net influence on the initial elevations in muscle blood flow at the beginning of exercise, 2) sympathetic nerves are involved in regulating muscle blood flow during steady-state submaximal exercise in conscious rats, and 3) these changes are seen in muscles of all fiber types.

Distribution of blood flow in muscles of miniature swine during exercise

1987 ◽  
Vol 62 (3) ◽  
pp. 1285-1298 ◽  
Author(s):  
R. B. Armstrong ◽  
M. D. Delp ◽  
E. F. Goljan ◽  
M. H. Laughlin
Keyword(s):  
Blood Flow ◽  
Exercise Intensity ◽  
Skeletal Muscles ◽  
Muscle Blood Flow ◽  
Peak Exercise ◽  
Fiber Types ◽  
Miniature Swine ◽  
Blood Flows ◽  
Limb Muscles ◽  
Total Muscle

The purpose of this study was to determine how the distribution of blood flow within and among the skeletal muscles of miniature swine (22 +/- 1 kg body wt) varies as a function of treadmill speed. Radiolabeled microspheres were used to measure cardiac output (Q) and tissue blood flows in preexercise and at 3–5 min of treadmill exercise at 4.8, 8.0, 11.3, 14.5, and 17.7 km/h. All pigs (n = 8) attained maximal O2 consumption (VO2max) (60 +/- 4 ml X min-1 X kg-1) by the time they ran at 17.7 km/h. At VO2max, 87% of Q (9.9 +/- 0.5 l/min) was to skeletal muscle, which constituted 36 +/- 1% of body mass. Average total muscle blood flow at VO2max was 127 +/- 14 ml X min-1 X 100 g-1; average limb muscle flow was 135 +/- 17 ml X min-1 X 100 g-1. Within the limb muscles, blood flow was distributed so that the deep red parts of extensor muscles had flows about two times higher than the more superficial white portions of the same muscles; the highest muscle blood flows occurred in the elbow flexors (brachialis: 290 +/- 44 ml X min-1 X 100 g-1). Peak exercise blood flows in the limb muscles were proportional (P less than 0.05) to the succinate dehydrogenase activities (r = 0.84), capillary densities (r = 0.78), and populations of oxidative (slow-twitch oxidative + fast-twitch oxidative-glycolytic) fiber types (r = 0.93) in the muscles. Total muscle blood flow plotted as a function of exercise intensity did not peak until the pigs attained VO2max, although flows in some individual muscles showed a plateau in this relationship at submaximal exercise intensities. The data demonstrate that blood flow in skeletal muscles of miniature swine is distributed heterogeneously and varies in relation to fiber type composition and exercise intensity.

Relation of blood flow to VO2, PO2, and PCO2 in dog gastrocnemius muscle

1988 ◽  
Vol 255 (5) ◽  
pp. H1004-H1010 ◽  
Author(s):  
D. E. Mohrman ◽  
R. R. Regal
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Gastrocnemius Muscle ◽  
Muscle Blood Flow ◽  
Carbon Dioxide Tension ◽  
Experimental Conditions ◽  
Muscle Oxygen ◽  
Muscle Oxygen Consumption ◽  
Relationship Of ◽  
The Relationship

We pump-perfused gastrocnemius-plantaris muscle preparations at constant pressure to study the relationship of muscle blood flow (Q) to muscle oxygen consumption (VO2), venous oxygen tension (PVO2), and venous carbon dioxide tension (PVCO2) during steady-state exercise at different rates. Tests were performed under four experimental conditions produced by altering the perfusate blood-gas status with a membrane lung. The consistency of the relationship of Q to other variables was evaluated by statistical analysis of fitted curves. Not one of the above listed variables had the same relationship with Q in all four of the experimental conditions we tested. However, we did find that a consistent relationship existed among Q, PVO2, and PVCO2 in our data. That relationship is well described by the equation (Q-23).[PVO2 - (0.5.PVCO2) - 3] = 105 (when Q is expressed in ml.100 g-1.min-1 and PVO2 and PVCO2 in mmHg). One interpretation of this result is that both PO2 and PCO2 are important variables in the control of blood flow in skeletal muscle the combined influence of which could account for nearly all of the hyperemia response to steady-state muscle exercise.

scholarly journals Exercise-induced hyperemia is associated with knee extensor fatigability in adults with type 2 diabetes

2019 ◽  
Vol 126 (3) ◽  
pp. 658-667 ◽  
Author(s):  
Jonathon W. Senefeld ◽  
Jacqueline K. Limberg ◽  
Kathleen M. Lukaszewicz ◽  
Sandra K. Hunter
Keyword(s):  
Type 2 Diabetes ◽  
Blood Flow ◽  
Lower Limb ◽  
Contractile Function ◽  
Muscle Blood Flow ◽  
Knee Extensor ◽  
Dynamic Exercise ◽  
Extensor Muscles ◽  
Exercise Induced

The aim of this study was to compare fatigability, contractile function, and blood flow to the knee extensor muscles after dynamic exercise in patients with type 2 diabetes mellitus (T2DM) and controls. The hypotheses were that patients with T2DM would demonstrate greater fatigability than controls, and greater fatigability would be associated with a lower exercise-induced increase in blood flow and greater impairments in contractile function. Patients with T2DM ( n = 15; 8 men; 62.4 ± 9.0 yr; 30.4 ± 7.7 kg/m2; 7,144 ± 3,294 steps/day) and 15 healthy control subjects (8 men, 58.4 ± 6.9 yr; 28.4 ± 4.6 kg/m2; 7,893 ± 2,323 steps/day) were matched for age, sex, body mass index, and physical activity. Fatigability was quantified as the reduction in knee extensor power during a 6-min dynamic exercise. Before and after exercise, vascular ultrasonography and electrical stimulation were used to assess skeletal muscle blood flow and contractile properties, respectively. Patients with T2DM had greater fatigability (30.0 ± 20.1% vs. 14.6 ± 19.0%, P < 0.001) and lower exercise-induced hyperemia (177 ± 90% vs. 194 ± 79%, P = 0.04) than controls but similar reductions in the electrically evoked twitch amplitude (37.6 ± 24.8% vs. 31.6 ± 30.1%, P = 0.98). Greater fatigability of the knee extensor muscles was associated with postexercise reductions in twitch amplitude ( r = 0.64, P = 0.001) and lesser exercise-induced hyperemia ( r = −0.56, P = 0.009). Patients with T2DM had greater lower-limb fatigability during dynamic exercise, which was associated with reduced contractile function and lower skeletal muscle blood flow. Thus, treatments focused on enhancing perfusion and reversing impairments in contractile function in patients with T2DM may offset lower-limb fatigability and aid in increasing exercise capacity. NEW & NOTEWORTHY Although prior studies compare patients with type 2 diabetes mellitus (T2DM) with lean controls, our study includes controls matched for age, body mass, and physical activity to more closely assess the effects of T2DM. Patients with T2DM demonstrated no impairment in macrovascular endothelial function, evidenced by similar flow-mediated dilation to controls. However, patients with T2DM had greater fatigability and reduced exercise-induced increase in blood flow (hyperemia) after a lower-limb dynamic fatiguing exercise compared with controls.

Enhanced arteriolar α-adrenergic constriction impairs dilator responses and skeletal muscle perfusion in obese Zucker rats

2004 ◽  
Vol 97 (2) ◽  
pp. 764-772 ◽  
Author(s):  
Jefferson C. Frisbee
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Gastrocnemius Muscle ◽  
Muscle Blood Flow ◽  
Zucker Rats ◽  
Metabolic Demand ◽  
Obese Zucker Rats ◽  
Isometric Twitch ◽  
Gastrocnemius Muscles

The present study tested the hypothesis that enhanced vascular α-adrenergic constriction in obese Zucker rats (OZR) impairs arteriolar dilation and perfusion of skeletal muscle at rest and with increased metabolic demand. In lean Zucker rats (LZR) and OZR, isolated gracilis arterioles were viewed via television microscopy, and the contralateral cremaster muscle or gastrocnemius muscle was prepared for study in situ. Gracilis and cremasteric arterioles were challenged with dilator stimuli under control conditions and after blockade of α-adrenoreceptors with prazosin, phentolamine, or yohimbine. Gastrocnemius muscles performed isometric twitch contractions of increasing frequency, and perfusion was continuously monitored. In OZR, dilator responses of arterioles to hypoxia (gracilis), wall shear rate (cremaster), acetylcholine, and iloprost (both) were impaired vs. LZR. Treatment with prazosin and phentolamine (and in cremasteric arterioles only, yohimbine) improved arteriolar reactivity to these stimuli in OZR, although responses remained impaired vs. LZR. Gastrocnemius muscle blood flow was reduced at rest in OZR; this was corrected with intravenous infusion of phentolamine or prazosin. At all contraction frequencies, blood flow was reduced in OZR vs. LZR; this was improved by infusion of phentolamine or prazosin at low-moderate metabolic demand only (1 and 3 Hz). At 5 Hz, adrenoreceptor blockade did not alter blood flow in OZR from levels in untreated rats. These results suggest that enhanced α-adrenergic constriction of arterioles of OZR contributes to impaired dilator responses and reduced muscle blood flow at rest and with mild-moderate (although not with large) elevations in metabolic demand.

Respiratory muscle blood flows during physiological and chemical hyperpnea in the rat

2000 ◽  
Vol 88 (1) ◽  
pp. 186-194 ◽  
Author(s):  
David C. Poole ◽  
William L. Sexton ◽  
Bradley J. Behnke ◽  
Christine S. Ferguson ◽  
K. Sue Hageman ◽  
...  
Keyword(s):  
Blood Flow ◽  
Respiratory Muscle ◽  
Maximal Exercise ◽  
Vastus Lateralis ◽  
Muscle Blood Flow ◽  
Oxidative Capacity ◽  
Blood Flows ◽  
Vasodilator Reserve ◽  
Exercise Muscle ◽  
Crural Diaphragm

Whether the diaphragm retains a vasodilator reserve at maximal exercise is controversial. To address this issue, we measured respiratory and hindlimb muscle blood flows and vascular conductances using radiolabeled microspheres in rats running at their maximal attainable treadmill speed (96 ± 5 m/min; range 71–116 m/min) and at rest while breathing either room air or 10% O2-8% CO2 (balance N2). All hindlimb and respiratory muscle blood flows measured increased during exercise ( P < 0.001), whereas increases in blood flow while breathing 10% O2-8% CO2 were restricted to the diaphragm only. During exercise, muscle blood flow increased up to 18-fold above rest values, with the greatest mass specific flows (in ml ⋅ min−1 ⋅ 100 g−1) found in the vastus intermedius (680 ± 44), red vastus lateralis (536 ± 18), red gastrocnemius (565 ± 47), and red tibialis anterior (602 ± 44). During exercise, blood flow was higher ( P < 0.05) in the costal diaphragm (395 ± 31 ml ⋅ min−1 ⋅ 100 g−1) than in the crural diaphragm (286 ± 17 ml ⋅ min−1 ⋅ 100 g−1). During hypoxia+hypercapnia, blood flows in both the costal and crural diaphragms (550 ± 70 and 423 ± 53 ml ⋅ min−1 ⋅ 100 g−1, respectively) were elevated ( P < 0.05) above those found during maximal exercise. These data demonstrate that there is a substantial functional vasodilator reserve in the rat diaphragm at maximal exercise and that hypoxia + hypercapnia-induced hyperpnea is necessary to elevate diaphragm blood flow to a level commensurate with its high oxidative capacity.

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