PT  - JOURNAL ARTICLE
AU  - RALF G. RAHWAN
AU  - J. L. BOROWITZ
AU  - T. S. MIYA
TI  - THE ROLE OF INTRACELLULAR CALCIUM IN CATECHOLAMINE SECRETION FROM THE BOVINE ADRENAL MEDULLA
DP  - 1973 Jan 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 106--118
VI  - 184
IP  - 1
4099  - http://jpet.aspetjournals.org/content/184/1/106.short
4100  - http://jpet.aspetjournals.org/content/184/1/106.full
SO  - J Pharmacol Exp Ther1973 Jan 01; 184
AB  - Concentration-effect curves were obtained using isolated perfused (5 ml min : 25°C) bovine adrenals stimulated with chlorpromazine, caffeine or d-amphetamine. with and without calcium in the medium. The presence of extracellular calcium had no effect on catecholamine release by chlorpromazine or high concentrations of d-amphetamine but enhanced the response to caffeine or low concentrations of d-amphetamine. Procaine (10-3 M) blocked the effect of extracellular calcium but had no effect on drug-evoked secretion in calcium-free medium. Magnesium (5 x 10-3 M), by contrast, blocked drug-evoked release in time absence of calcium. Catecholamine release induced by chlorpromazine (10-3 M), caffeine (10-1 M) or d-amphetamine (5 x 10-2 in calcium-free medium generally paralleled 40Ca and 45Ca efflux from radiocalcium-labeled glands. However, d-amphetamine initially released catecholamines without significant effect on calcium efflux, although release of both substances increased after termination of time stimulus. Chlorpromazine and caffeine mobilized 45Ca from adrenal medullary mitochondria. Caffeine and d-amphetamine mobilized 45Ca from the endoplasmic reticulum. It is proposed that chlorpromazine, caffeine or d-amphetamine can evoke catecholamine release by mobilizing different calcium pools within the adrenal medullary chromaffin cell and that magnesium can block this effect. © 1973 by The Williams & Wilkins Company