Functional Sympatholysis During Muscular Activity

The effects of both direct and reflexly induced increases in sympathetic activity on the blood flow to an extremity at rest and during muscular activity have been studied. When the O₂ uptake of an extremity is increased during muscular activity, its vascular resistance falls sharply with a small increase in O₂ uptake and thereafter declines only slightly. The responsiveness of a vascular bed to adrenergic stimulation diminishes sharply with a small increase in O₂ uptake and thereafter diminishes only slightly. The role of the carotid sinus as a sense organ which helps to regulate blood flow to the various tissues of the organism in accordance with their varying metabolic requirements rather than one which acts only as a receptor that helps to safeguard flow to the vital organs has been discussed.