Effect of cooling on beta-receptor mechanisms in isolated cutaneous veins of the dog

Abstract

Alpha-adrenergic activation of cutaneous veins by nerve stimulation or norepinephrine has been shown to be facilitated by a decrease in temperature. In the present study, the effects of cooling on beta-adrenergic mechanisms in the cutaneous veins were investigated by recording changes in isometric tension in helical strips of saphenous veins. At 37°, low doses of isoproterenol had negligible relaxing effects on the preparations but reduced their reactivity to electric stimulation; in higher doses, isoproterenol caused contraction of the saphenous vein strips. Cooling the bath to 29° slightly decreased the basal tension of the preparations and markedly augmented the contracting effect of higher doses of isoproterenol. The depressing action of that drug on the reactivity to electric stimulation was markedly accentuated by cooling. In the presence of alpha-adrenolytic drugs, the relaxing action of norepinephrine was also facilitated by a decrease in temperature. Thus, in the cutaneous vein of the dog, both the venodilator (beta-adrenergic) and the venoconstrictor (alpha-adrenergic) actions of catecholamines are facilitated by a decrease in temperature. © 1970.