Vasoactive intestinal peptide is a secretagogue in bovine chromaffin cells pretreated with pertussis toxin.
Vasoactive intestinal peptide (VIP) evokes little or no secretion of catecholamines from cultured bovine chromaffin cells. However, pretreatment of chromaffin cells with pertussis toxin (PTX, 100 ng/ml for > or = 4 h) revealed that VIP is a secretagogue. In PTX-treated cells catecholamine secretion evoked by VIP occurs with minimal elevation of cyclic AMP and is only slightly enhanced by cyclic nucleotide phosphodiesterase inhibitors. Forskolin, a direct activator of adenylate cyclase, causes delayed secretion of catecholamines from chromaffin cells treated with PTX, but only with pronounced elevation of cyclic AMP levels. Stimulation of catecholamine secretion by histamine, known to activate phosphatidylinositol-specific phospholipase C in chromaffin cells, is also enhanced by preincubation of the cells with PTX. These results suggest that in the bovine chromaffin cell a PTX-sensitive G-protein mediates tonic inhibition of secretion, possibly by preventing activation of phospholipase C.
Wilson
S P
SP
Department of Pharmacology, University of South Carolina School of Medicine, Columbia 29208.
D037361:Adenylate Cyclase Toxin; D000313:Adrenal Medulla / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D002395:Catecholamines / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology; D006632:Histamine / Q000494:pharmacology; D037342:Pertussis Toxin; D010716:Phosphatidylinositols / Q000502:physiology; D015290:Second Messenger Systems / Q000502:physiology; D014660:Vasoactive Intestinal Peptide / Q000502:physiology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D037361:Adenylate Cyclase Toxin; D002395:Catecholamines; D010716:Phosphatidylinositols; D010566:Virulence Factors, Bordetella; D005576:Colforsin; D014660:Vasoactive Intestinal Peptide; D006632:Histamine; D000242:Cyclic AMP; D037342:Pertussis Toxin