Phorbol Esters Cause Preferential Secretion of Norepinephrine from Bovine Chromafin Cells

Publisher Website
Google Scholar
Abstract
Differential secretion of norepinephrine and epinephrine was studied in cultured bovine chromaffin cells. Nicotinic agonists and 55 mM K+ evoked a slightly greater release of norepinephrine than of epinephrine: The percentage of norepinephrine secreted was 1.5 to two times greater than the percentage of epinephrine secreted. In contrast, when the cells were treated with phorbol 12,13‐dibutyrate, the percentage of norepinephrine released was six to eight times greater than that of epinephrine released. Similar results were obtained in experiments with cultures highly enriched in either norepinephrine‐containing cells or epinephrine‐containing cells. In response to 55 mM K+, catecholamine release from norepinephrine‐containing cells was two times greater than that from epinephrine‐containing cells. In response to phorbol 12,13‐dibutyrate, secretion from norepinephrine‐containing cells was 13 times greater than that from epinephrine‐containing cells. These results suggest that protein kinase C plays a specific role in the regulation of catecholamine secretion from norepinephrine‐containing cells.