α-Adrenergic vasoconstriction in active skeletal muscles during dynamic exercise

1999 ◽  
Vol 277 (1) ◽  
pp. H33-H39 ◽  
Author(s):  
John B. Buckwalter ◽  
Philip S. Clifford
Keyword(s):  
Blood Flow ◽  
Exercise Intensity ◽  
Adrenergic Receptor ◽  
Skeletal Muscles ◽  
Systemic Blood Pressure ◽  
Dynamic Exercise ◽  
Iliac Arteries ◽  
Adrenergic Antagonist ◽  
Sympathetic Vasoconstriction ◽  
Adrenergic Antagonists

Sympathetic vasoconstriction in working muscles during dynamic exercise has been demonstrated by intra-arterial administration of α1-adrenergic antagonists. The purpose of this study was to examine the existence of α1- and α2-adrenergic receptor-mediated vasoconstriction in active skeletal muscles during exercise. Six mongrel dogs were instrumented chronically with flow probes on the external iliac arteries of both hindlimbs, and a catheter was inserted in one femoral artery. All dogs ran on a motorized treadmill at three exercise intensities (3 miles/h, 6 miles/h, and 6 miles/h at 10% grade) on separate days. After 5 min of exercise, a selective α1- (prazosin) or a selective α2-adrenergic antagonist (rauwolscine) was infused as a bolus into the femoral arterial catheter (only one drug per day). The doses of the antagonists were adjusted to maintain the same effective concentration at each exercise intensity. At the mild, moderate, and heavy workloads prazosin infusion produced immediate increases in iliac conductance of 65 ± 9, 35 ± 6, and 18 ± 4% (means ± SE), respectively, and increases in blood flow of 290 ± 24, 216 ± 23, and 172 ± 18 ml/min, respectively. Rauwolscine infusion produced increases in conductance of 52 ± 5%, 36 ± 5%, and 26 ± 3%, respectively, and blood flow increases of 250 ± 34, 244 ± 39, and 259 ± 35 ml/min at the three workloads. Systemic blood pressure and blood flow in the contralateral iliac artery were unaffected by any of the antagonist infusions. These results demonstrate that there is ongoing α1- and α2-adrenergic receptor-mediated vasoconstriction in exercising skeletal muscles even at heavy workloads and that the magnitude of vasoconstriction decreases as exercise intensity increases.

scholarly journals Sympathetic vasoconstriction in active skeletal muscles during dynamic exercise

1997 ◽  
Vol 83 (5) ◽  
pp. 1575-1580 ◽  
Author(s):  
John B. Buckwalter ◽  
Patrick J. Mueller ◽  
Philip S. Clifford
Keyword(s):  
Femoral Artery ◽  
Skeletal Muscles ◽  
Systemic Blood Pressure ◽  
Dynamic Exercise ◽  
Systemic Blood ◽  
Iliac Arteries ◽  
Adrenergic Antagonist ◽  
Sympathetic Vasoconstriction ◽  
Adrenergic Antagonists ◽  
Arterial Blockade

Buckwalter, John B., Patrick J. Mueller, and Philip S. Clifford. Sympathetic vasoconstriction in active skeletal muscles during dynamic exercise. J. Appl. Physiol. 83(5): 1575–1580, 1997.—Studies utilizing systemic administration of α-adrenergic antagonists have failed to demonstrate sympathetic vasoconstriction in working muscles during dynamic exercise. The purpose of this study was to examine the existence of active sympathetic vasoconstriction in working skeletal muscles by using selective intra-arterial blockade. Six mongrel dogs were instrumented chronically with flow probes on the external iliac arteries of both hindlimbs and with a catheter in one femoral artery. All dogs ran on a motorized treadmill at three intensities on separate days. After 2 min, the selective α1-adrenergic antagonist prazosin (0.1 mg) was infused as a bolus into the femoral artery catheter. At mild, moderate, and heavy workloads, there were immediate increases in iliac conductance of 76 ± 7, 54 ± 11, and 22 ± 6% (mean ± SE), respectively. Systemic blood pressure and blood flow in the contralateral iliac artery were unaffected. These results demonstrate that there is sympathetic vasoconstriction in active skeletal muscles even at high exercise intensities.

α1-Adrenergic-receptor responsiveness in skeletal muscle during dynamic exercise

1998 ◽  
Vol 85 (6) ◽  
pp. 2277-2283 ◽  
Author(s):  
John B. Buckwalter ◽  
Patrick J. Mueller ◽  
Philip S. Clifford
Keyword(s):  
Femoral Artery ◽  
Adrenergic Receptor ◽  
Skeletal Muscles ◽  
Systemic Blood Pressure ◽  
Dynamic Exercise ◽  
Systemic Blood ◽  
Iliac Arteries ◽  
Selective Agonist ◽  
Sympathetic Vasoconstriction ◽  
Adrenergic Receptor Agonist

Attenuation of sympathetic vasoconstriction (sympatholysis) in working muscles during dynamic exercise is controversial. One potential mechanism is a reduction in α1-adrenergic-receptor responsiveness. The purpose of this study was to examine α1-adrenergic-receptor-mediated vasoconstriction in resting and working skeletal muscles by using intra-arterial infusions of a selective agonist. Seven mongrel dogs were instrumented chronically with flow probes on the external iliac arteries of both hindlimbs and a catheter in one femoral artery. A selective α1-adrenergic-receptor agonist (phenylephrine) was infused as a bolus into the femoral artery catheter at rest and during exercise. All dogs ran on a motorized treadmill at two exercise intensities (3 and 6 miles/h). Intra-arterial infusions of the same effective concentration of phenylephrine elicited reductions in vascular conductance of 76 ± 4, 76 ± 6, and 67 ± 5% ( P > 0.05) at rest, 3 miles/h, and 6 miles/h, respectively. Systemic blood pressure and blood flow in the contralateral iliac artery were unaffected by phenylephrine. These results do not demonstrate an attenuation of vasoconstriction to a selective α1-agonist during exercise and do not support the concept of sympatholysis.

Exercise attenuates α-adrenergic-receptor responsiveness in skeletal muscle vasculature

2001 ◽  
Vol 90 (1) ◽  
pp. 172-178 ◽  
Author(s):  
John B. Buckwalter ◽  
Jay S. Naik ◽  
Zoran Valic ◽  
Philip S. Clifford
Keyword(s):  
Skeletal Muscle ◽  
Femoral Artery ◽  
Adrenergic Receptor ◽  
Systemic Blood Pressure ◽  
Heavy Exercise ◽  
Adrenergic Agonist ◽  
Vascular Conductance ◽  
Iliac Arteries ◽  
Sympathetic Vasoconstriction ◽  
Selective Agonists

Attenuation of sympathetic vasoconstriction (sympatholysis) in working muscles during dynamic exercise is controversial. A potential mechanism is a reduction in α-adrenergic-receptor responsiveness. The purpose of this study was to examine α1- and α2-adrenergic-receptor-mediated vasoconstriction in resting and exercising skeletal muscle using intra-arterial infusions of selective agonists. Thirteen mongrel dogs were instrumented chronically with flow probes on the external iliac arteries of both hindlimbs and a catheter in one femoral artery. The selective α1-adrenergic agonist (phenylephrine) or the selective α2-adrenergic agonist (clonidine) was infused as a bolus into the femoral artery catheter at rest and during mild and heavy exercise. Intra-arterial infusions of phenylephrine elicited reductions in vascular conductance of 76 ± 4, 71 ± 5, and 31 ± 2% at rest, 3 miles/h, and 6 miles/h and 10% grade, respectively. Intra-arterial clonidine reduced vascular conductance by 81 ± 5, 49 ± 4, and 14 ± 2%, respectively. The response to intra-arterial infusion of clonidine was unaffected by surgical sympathetic denervation. Agonist infusion did not affect either systemic blood pressure, heart rate, or blood flow in the contralateral iliac artery. α1-Adrenergic-receptor responsiveness was attenuated during heavy exercise. In contrast, α2-adrenergic-receptor responsiveness was attenuated even at a mild exercise intensity. These results suggest that the mechanism of exercise sympatholysis may involve reductions in postsynaptic α-adrenergic-receptor responsiveness.

Autonomic control of skeletal muscle vasodilation during exercise

1997 ◽  
Vol 83 (6) ◽  
pp. 2037-2042 ◽  
Author(s):  
John B. Buckwalter ◽  
Patrick J. Mueller ◽  
Philip S. Clifford
Keyword(s):  
Blood Pressure ◽  
Skeletal Muscle ◽  
Blood Flow ◽  
Muscarinic Receptors ◽  
Systemic Blood Pressure ◽  
Dynamic Exercise ◽  
Autonomic Control ◽  
Extensive Investigation ◽  
Systemic Blood ◽  
Iliac Arteries

Buckwalter, John B., Patrick J. Mueller, and Philip S. Clifford. Autonomic control of skeletal muscle vasodilation during exercise. J. Appl. Physiol. 83(6): 2037–2042, 1997.—Despite extensive investigation, the control of blood flow during dynamic exercise is not fully understood. The purpose of this study was to determine whether β-adrenergic or muscarinic receptors are involved in the vasodilation in exercising skeletal muscle. Six mongrel dogs were instrumented with ultrasonic flow probes on both external iliac arteries and with a catheter in a branch of one femoral artery. The dogs exercised on a treadmill at 6 miles/h while drugs were injected intra-arterially into one hindlimb. Isoproterenol (0.2 μg) or acetylcholine (1 μg) elicited increases in iliac blood flow of 89.8 ± 14.4 and 95.6 ± 17.4%, respectively, without affecting systemic blood pressure or blood flow in the contralateral iliac artery. Intra-arterial propranolol (1 mg) or atropine (500 μg) had no effect on iliac blood flow, although they abolished the isoproterenol and acetylcholine-induced increases in iliac blood flow. These data indicate that exogenous activation of β-adrenergic or muscarinic receptors in the hindlimb vasculature increases blood flow to dynamically exercising muscle. More importantly, because neither propranolol nor atropine affected iliac blood flow, we conclude that β-adrenergic and muscarinic receptors are not involved in the control of blood flow to skeletal muscle during moderate steady-state dynamic exercise in dogs.

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.

α2-Adrenergic agonists protect against radiocontrast-induced nephropathy in mice

2008 ◽  
Vol 295 (3) ◽  
pp. F741-F748 ◽  
Author(s):  
F. T. Billings ◽  
Sean W. C. Chen ◽  
Mihwa Kim ◽  
Sang Won Park ◽  
Joseph H. Song ◽  
...  
Keyword(s):  
Blood Flow ◽  
Proximal Tubule ◽  
Adrenergic Receptor ◽  
Perioperative Period ◽  
Clinical Problem ◽  
Systemic Blood Pressure ◽  
Microvascular Endothelial Cell ◽  
Protective Effects ◽  
Receptor Agonists ◽  
Microvascular Endothelial

Radiocontrast nephropathy (RCN) is a common clinical problem for which there is no effective therapy. Utilizing a murine model, we tested the hypothesis that α2-adrenergic receptor agonists (clonidine and dexmedetomidine) protect against RCN induced with iohexol (a nonionic low-osmolar radiocontrast). C57BL/6 mice were pretreated with saline, clonidine, or dexmedetomidine before induction of RCN. Some mice were pretreated with yohimbine (a selective α2-receptor antagonist) before saline, clonidine, or dexmedetomidine administration. α2-Agonist-treated mice had reduced plasma creatinine, renal tubular necrosis, renal apoptosis, and renal cortical proximal tubule vacuolization 24 h after iohexol injection. Yohimbine reversed the protective effects of clonidine and dexmedetomidine pretreatment. Injection of iohexol resulted in a rapid (∼90 min) fall of renal outer medullary blood flow. Clonidine and dexmedetomidine pretreatment significantly attenuated this perfusion decrease without changing systemic blood pressure. To determine whether proximal tubular α2-adrenergic receptors mediate the cytoprotective effects, we treated cultured human proximal tubule (HK-2) cells and rat pulmonary microvascular endothelial cells with iohexol after vehicle, clonidine, or dexmedetomidine pretreatment. Iohexol caused a direct dose-dependent reduction of HK-2 and rat pulmonary microvascular endothelial cell viability, but α2-agonists failed to preserve the viability of both cell types. We conclude that α2-adrenergic receptor agonists protect mice against RCN by preserving outer medullary renal blood flow. As α2-agonists are widely utilized during the perioperative period, our findings may have significant clinical relevance to improving outcomes following radiocontrast exposure.

Skeletal muscle vasodilation at the onset of exercise

1998 ◽  
Vol 85 (5) ◽  
pp. 1649-1654 ◽  
Author(s):  
John B. Buckwalter ◽  
Stephen B. Ruble ◽  
Patrick J. Mueller ◽  
Philip S. Clifford
Keyword(s):  
Blood Pressure ◽  
Skeletal Muscle ◽  
Blood Flow ◽  
Muscarinic Receptors ◽  
Treadmill Exercise ◽  
Systemic Blood Pressure ◽  
Systemic Blood ◽  
Iliac Arteries ◽  
Blood Flows ◽  
Peak Blood

The purpose of this study was to determine whether β-adrenergic or muscarinic receptors are involved in skeletal muscle vasodilation at the onset of exercise. Mongrel dogs ( n = 7) were instrumented with flow probes on both external iliac arteries and a catheter in one femoral artery. Propranolol (1 mg), atropine (500 μg), both drugs, or saline was infused intra-arterially immediately before treadmill exercise at 3 miles/h, 0% grade. Immediate and rapid increases in iliac blood flow occurred with initiation of exercise under all conditions. Peak blood flows were not significantly different among conditions (682 ± 35, 646 ± 49, 637 ± 68, and 705 ± 50 ml/min, respectively). Although the doses of antagonists employed had no effect on heart rate or systemic blood pressure, they were adequate to abolish agonist-induced increases in iliac blood flow. Because neither propranolol nor atropine affected iliac blood flow, we conclude that activation of β-adrenergic and muscarinic receptors is not essential for the rapid vasodilation in active skeletal muscle at the onset of exercise in dogs.

Effect of exercise intensity and AICAR on isoform-specific expressions of murine skeletal muscle PGC-1α mRNA: a role of β2-adrenergic receptor activation

2011 ◽  
Vol 300 (2) ◽  
pp. E341-E349 ◽  
Author(s):  
Miki Tadaishi ◽  
Shinji Miura ◽  
Yuko Kai ◽  
Emi Kawasaki ◽  
Keiichi Koshinaka ◽  
...  
Keyword(s):  
Exercise Intensity ◽  
High Intensity ◽  
Adrenergic Receptor ◽  
Skeletal Muscles ◽  
Receptor Activation ◽  
High Intensity Exercise ◽  
Treadmill Running ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Exercise Induced

There are three isoforms of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) mRNA, which promotes mitochondrial biogenesis in skeletal muscles. Compared with PGC-1α-a mRNA, PGC-1α-b or PGC-1α-c mRNA is transcribed by a different exon 1 of the PGC-1α gene. In this study, effects of exercise intensity and 5-aminoimidazole-4-carboxamide-1β-d-ribofuranoside (AICAR) on isoform-specific expressions of PGC-1α were investigated. All isoforms were increased in proportion to exercise intensity of treadmill running (10–30 m/min for 30 min). Preinjection of β2-adrenergic receptor (AR) antagonist (ICI 118551) inhibited the increase in PGC-1α-b and PGC-1α-c mRNAs, but not the increase in PGC-1α-a mRNA, in response to high-intensity exercise. Although high-intensity exercise activated α2-AMP-activated protein kinase (α2-AMPK) in skeletal muscles, inactivation of α2-AMPK activity did not affect high-intensity exercise-induced mRNA expression of all PGC-1α isoforms, suggesting that activation of α2-AMPK is not mandatory for an increase in PGC-1α mRNA by high-intensity exercise. A single injection in mice of AICAR, an AMPK activator, increased mRNAs of all PGC-1α isoforms. AICAR increased blood catecholamine concentrations, and preinjection of β2-AR antagonist inhibited the increase in PGC-1α-b and PGC-1α-c mRNAs but not the increase in PGC-1α-a mRNA. Direct exposure of epitrochlearis muscle to AICAR increased PGC-1α-a but not the -b isoform. These data indicate that exercise-induced PGC-1α expression was dependent on the intensity of exercise. Exercise or AICAR injection increased PGC-1α-b and PGC-1α-c mRNAs via β2-AR activation, whereas high-intensity exercise increased PGC-1α-a expression by a multiple mechanism in which α2-AMPK is one of the signaling pathways.

Facial Blood Flow Responses to Dynamic Exercise

2020 ◽  
Author(s):  
Naoyuki Hayashi ◽  
Hideaki Kashima ◽  
Tsukasa Ikemura
Keyword(s):  
Blood Flow ◽  
Exercise Intensity ◽  
Regional Differences ◽  
Regional Blood Flow ◽  
Dynamic Exercise ◽  
Laser Speckle ◽  
Laser Speckle Flowgraphy ◽  
Handgrip Exercise ◽  
Post Hoc ◽  
One Way Anova

AbstractWe reported previously that a static handgrip exercise evoked regional differences in the facial blood flow. The present study examined whether regional differences in facial blood flow are also evoked during dynamic exercise. Facial blood flow was measured by laser speckle flowgraphy during 15 min of cycling exercise at heart rates of 120 bpm, 140 bpm and 160 bpm in 12 subjects. The facial vascular conductance index was calculated from the blood flow and mean arterial pressure. The regional blood flow and conductance index values were determined in the forehead, eyelid, nose, cheek, ear and lip. One-way ANOVA and Tukey’s post-hoc test were used to examine effects of exercise intensity and target regions. The blood flow and conductance index in skin areas increased significantly with the exercise intensity. The blood flow and conductance index in the lip increased significantly at 120 bpm and 140 bpm compared to the control, while the values in the lip at 160 bpm did not change from the control values. These results suggest that the blood flow in facial skin areas, not in the lip, responds similarly to dynamic exercise, in contrast to the responses to static exercise.

scholarly journals Muscle metaboreflex activation during dynamic exercise vasoconstricts ischemic active skeletal muscle

2015 ◽  
Vol 309 (12) ◽  
pp. H2145-H2151 ◽  
Author(s):  
Jasdeep Kaur ◽  
Tiago M. Machado ◽  
Alberto Alvarez ◽  
Abhinav C. Krishnan ◽  
Hanna W. Hanna ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Threshold Level ◽  
Dynamic Exercise ◽  
Adrenergic Blockade ◽  
Muscle Metaboreflex ◽  
Group Iii ◽  
Arterial Blood ◽  
Sympathetic Vasoconstriction ◽  
Before And After

Metabolite accumulation due to ischemia of active skeletal muscle stimulates group III/IV chemosensitive afferents eliciting reflex increases in arterial blood pressure and sympathetic activity, termed the muscle metaboreflex. We and others have previously demonstrated sympathetically mediated vasoconstriction of coronary, renal, and forelimb vasculatures with muscle metaboreflex activation (MMA). Whether MMA elicits vasoconstriction of the ischemic muscle from which it originates is unknown. We hypothesized that the vasodilation in active skeletal muscle with imposed ischemia becomes progressively restrained by the increasing sympathetic vasoconstriction during MMA. We activated the metaboreflex during mild dynamic exercise in chronically instrumented canines via graded reductions in hindlimb blood flow (HLBF) before and after α1-adrenergic blockade [prazosin (50 μg/kg)], β-adrenergic blockade [propranolol (2 mg/kg)], and α1 + β-blockade. Hindlimb resistance was calculated as femoral arterial pressure/HLBF. During mild exercise, HLBF must be reduced below a threshold level before the reflex is activated. With initial reductions in HLBF, vasodilation occurred with the imposed ischemia. Once the muscle metaboreflex was elicited, hindlimb resistance increased. This increase in hindlimb resistance was abolished by α1-adrenergic blockade and exacerbated after β-adrenergic blockade. We conclude that metaboreflex activation during submaximal dynamic exercise causes sympathetically mediated α-adrenergic vasoconstriction in ischemic skeletal muscle. This limits the ability of the reflex to improve blood flow to the muscle.

Sign in / Sign up

Export Citation Format

Share Document