Effects of local cooling on adrenergic neurotransmission in the dog's cutaneous vein

Abstract

Experiments were performed to investigate whether local cooling facilitates adrenergic neurotransmission in the dog's cutaneous vein. Helical strips of saphenous veins were incubated with 3H norepinephrine, and mounted for isometric tension recording and superfusion. The superfusate was collected for measurement of total radioactivity, or for chromatographic analysis. Electric stimulation (2 Hz) caused contraction and augmented the efflux of 3H norepinephrine and metabolites. Cooling (from 37 to 28° C) imposed during electric stimulation caused a further increase in tension, but decreased the amount of 3H norepinephrine and metabolites overflowing into the superfusate. These experiments demonstrate that the potentiating effect of cooling on the response of cutaneous veins to sympathetic nerve stimulation is not due in part to facilitation of adrenergic neurotransmission, but only reflects the greater affinity of the smooth muscle cells for the liberated transmitter.