p-chloromercuribenzoate causes Ca2+-dependent exocytotic catecholamine secretion from cultured bovine adrenal medullary cells.
Incubation of cultured bovine adrenal medullary cells with p-chloromercuribenzoate (50-500 microM), a sulfhydryl-reacting agent, caused an increase in the secretion of catecholamines, p-Chloromercuriphenyl sulfonate, a p-chloromercuribenzoate analogue that poorly penetrates the cell membrane, caused a similar increase in catecholamine secretion. In both cases, catecholamine secretion was dependent on extracellular Ca2+. Furthermore, p-chloromercuribenzoate caused both 45Ca2+ influx into the cells and an increase in the intracellular free Ca2+ concentration. The increases in catecholamine secretion and 45Ca2+ influx behaved similarly in relation to p-chloromercuribenzoate concentration. The time courses of the increased secretion, 45Ca2+ influx, and intracellular free Ca2+ concentration by p-chloromercuribenzoate were also quite similar. The stimulation of catecholamine secretion by p-chloromercuribenzoate was reversed by washing the cells with dithiothreitol-containing medium, but not by dithiothreitol-free medium. When the cells were treated with p-chloromercuribenzoate, dopamine-beta-hydroxylase, an enzyme present in the chromaffin granules along with catecholamines, was also released. However, p-chloromercuribenzoate did not cause release of phenylethanolamine-N-methyltransferase, an enzyme present in the cytoplasm. These results indicate that catecholamine secretion due to p-chloromercuribenzoate occurs by Ca2+-dependent exocytosis.
Tachikawa
E
E
Department of Pharmacology, School of Medicine, Iwate Medical University, Morioka, Japan.
Takahashi
S
S
Kashimoto
T
T
D000313:Adrenal Medulla / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D002729:Chloromercuribenzoates / Q000494:pharmacology*; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism; D005089:Exocytosis; D009994:Osmolar Concentration; D010625:Phenylethanolamine N-Methyltransferase / Q000378:metabolism; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D020245:p-Chloromercuribenzoic Acid
D002395:Catecholamines; D002729:Chloromercuribenzoates; D013439:Sulfhydryl Reagents; D020245:p-Chloromercuribenzoic Acid; D004299:Dopamine beta-Hydroxylase; D010625:Phenylethanolamine N-Methyltransferase; D002118:Calcium