Release of catecholamines from perfused cat adrenal gland by veratridine

Experiments were undertaken to verify the existence of fast sodium channels in the adrenal chromaffin cell membrane and to assess their contribution to the physiological release of catecholamines. We have used veratridine to activate sodium channels. Veratridine causes secretion of catecholamines from perfused cat adrenal gland. Secretory response to veratridine is calcium dependent and abolished by tetrodotoxin. Secretion of catecholamines by acetylcholine is only partially blocked by tetrodotoxin. It is concluded that the adrenal chromaffin cell membrane contains fast sodium channels directly comparable to those of impulse-propagating neurons, but they do not appear to be essential in the secretory response to acetylcholine or splanchnic nerve stimulation.