title: Autonomic control of skeletal muscle vasodilation during exercise.
abstract: Despite extensive investigation, the control of blood flow during dynamic exercise is not fully understood. The purpose of this study was to determine whether beta-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 microg) or acetylcholine (1 microg) 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 microg) 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 beta-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 beta-adrenergic and muscarinic receptors are not involved in the control of blood flow to skeletal muscle during moderate steady-state dynamic exercise in dogs.
authors.affiliation: Department of Anesthesiology, Veterans Affairs Medical Center and Medical College of Wisconsin, Milwaukee, Wisconsin 53295, USA.
authors.forename: J B
authors.initials: JB
authors.lastname: Buckwalter
authors.forename: P J
authors.initials: PJ
authors.lastname: Mueller
authors.forename: P S
authors.initials: PS
authors.lastname: Clifford
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D004285:Dogs; D006339:Heart Rate / Q000502:physiology; D006614:Hindlimb / Q000098:blood supply / Q000502:physiology; D007545:Isoproterenol / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000294:innervation*; D005082:Physical Exertion / Q000502:physiology*; D011433:Propranolol / Q000494:pharmacology; D012039:Regional Blood Flow / Q000502:physiology; D014664:Vasodilation / Q000502:physiology*
chemical_list: D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D018727:Muscarinic Antagonists; D001285:Atropine; D011433:Propranolol; D007545:Isoproterenol