Distribution of exogenous acetaldehyde in cow adrenal medulla chromaffin granules

Abstract

Release of catecholamines from the cow perfused isolated adrenal gland was induced by infusion of acetaldehyde in concentrations between 5 times 10−4 and 3·5 times 10−1m. There was a significant correlation between the concentration of acetaldehyde and catecholamine release. Analysis of homogenates of medullae from glands stimulated with [14C]acetaldehyde showed that the specific activity (14C mg−1 protein) was higher in chromaffin vesicles than in other tissue fractions. The major portion of the 14C of chromaffin vesicles was present as soluble tetrahydroisoquinoline derivatives. There was no correlation between catecholamine release and the amount of tetrahydroiso-quinolines formed. A small portion of the vesicle 14C was associated with the membrane, and there was a significant correlation between the membrane-bound 14C and catecholamine release. It is concluded that acetaldehyde can interact with the chromaffin vesicle membrane in a way that alters the ability of the vesicle to retain catecholamines which then diffuse out of the vesicle and into the circulation.