Skeletal muscle vasodilation at the onset of exercise.
The purpose of this study was to determine whether beta-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 microgram), 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 beta-adrenergic and muscarinic receptors is not essential for the rapid vasodilation in active skeletal muscle at the onset of exercise in dogs.
Buckwalter
J B
JB
Departments of Anesthesiology and Physiology, Medical College of Wisconsin and Veterans Affairs Medical Center, Milwaukee, Wisconsin 53295, USA.
Ruble
S B
SB
Mueller
P J
PJ
Clifford
P S
PS
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000502:physiology; D004285:Dogs; D006339:Heart Rate / Q000502:physiology; D006614:Hindlimb / Q000098:blood supply; D018721:Muscarinic Agonists / Q000494:pharmacology; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D011433:Propranolol / Q000494:pharmacology; D012039:Regional Blood Flow / Q000502:physiology; D014664:Vasodilation / Q000502:physiology*
D000319:Adrenergic beta-Antagonists; D018721:Muscarinic Agonists; D001285:Atropine; D011433:Propranolol