ALAMETHICIN-EVOKED CATECHOLAMINE RELEASE FROM CAT ADRENAL-GLANDS

Alamethicin enhances the rate of catecholamine output from perfused cat adrenal glands in a concentration-dependent manner. At 37°C, catecholamine released went from 4.29±0.25 to 20.51±0.63 ug/stimulus at ionophore concentrations ranging from 20 to 100 ug/ml. Secretion was abolished at 22°C or in the absence of extracellular Ca. The time-course of secretion (quick activation followed by a decline) evoked by alamethicin considerably differs from the catecholamine release pattern seen with A23187, X537A or ionomycin, which evoke a slowly developing, non-inactivating secretory response. In fact, its transient secretion pattern resembles that of nicotinic or high-K stimulation of cat adrenal glands, thus suggesting that alamethicin might form Ca permeable artificial channels in chromaffin cell plasma membranes. © 1990.