Pharmacological evidence for the involvement of Na+ channels in the release of catecholamines from perfused adrenal glands.

Veratridine (0.1 mM) was found to be effective in producing an increase in the catecholamine output from perfused guinea-pig adrenal glands in the presence of high concentrations of hexamethonium (1.83 mM) and atropine (28.8 micrometer). The response to veratridine was abolished by removal of either Na+ or Ca2+ from perfusion media and by the addition of tetrodotoxin (0.1 micrometer). It is suggested that the response to veratridine may be due to an increase in the tetrodotoxin-sensitive Na+ permeability of chromaffin cell membranes.