Is the transient nature of the secretory response of chromaffin cells due to inactivation of calcium channels?
Catecholamine release from chromaffin cells in response to carbamylcholine and high K+ is transient. Monitoring intracellular free calcium ([Ca2+]i) using quin2 demonstrated a transient rise in [Ca2+]i in response to carbamylcholine. The termination of secretion due to carbamylcholine is probably a consequence of the return of [Ca2+]i to resting levels as the nicotinic receptors desensitise. Depolarisation with 55 mM K+ led to a long-lasting rise in [Ca2+]i which persisted after the secretory response had terminated. The maintained rise in [Ca2+]i appeared to be due to continued opening of verapamil-sensitive Ca2+ channels. These results suggest that inactivation of voltage-dependent Ca2+ channels does not account for the transient nature of the secretory response in chromaffin cells.
Burgoyne
R D
RD
Cheek
T R
TR
D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002417:Cattle; D002837:Chromaffin Granules / Q000187:drug effects / Q000378:metabolism*; D002838:Chromaffin System / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D007473:Ion Channels / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D007473:Ion Channels; D004533:Egtazic Acid; D002217:Carbachol; D014700:Verapamil; D011188:Potassium; D002118:Calcium