omega-Conotoxin GVIA blocks nicotine-induced catecholamine secretion by blocking the nicotinic receptor-activated inward currents in bovine chromaffin cells.
We have studied the contribution of N-type voltage-dependent Ca2+ channels to both norepinephrine and epinephrine secretion from bovine chromaffin cells induced by high K+ or nicotine using omega-conotoxin GVIA, a selective blocker of N-type voltage-dependent Ca2+ channels. We found that high K+ (75 mM) induced catecholamine secretion was not affected by exposure of bovine chromaffin cells to omega-conotoxin GVIA (1 microM). However, nicotine-induced both norepinephrine and epinephrine secretion were similarly blocked (about 25%) by omega-conotoxin GVIA (1 microM). This effect could be explained by a potent (about 80%) and reversible blockade of the inward current induced by nicotine receptor activation in bovine chromaffin cells. The results indicate that besides the blockade of N-type voltage-dependent channels, omega-conotoxin GVIA is a potent and reversible blocker of the nicotinic receptor-induced currents in chromaffin cells.
Fernández
J M
JM
Departamento de Farmacología, Universidad de Alicante, Spain.
Granja
R
R
Izaguirre
V
V
González-García
C
C
Ceña
V
V
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D002838:Chromaffin System / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004563:Electrochemistry; D004837:Epinephrine / Q000378:metabolism; D009538:Nicotine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D018722:Nicotinic Agonists / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000378:metabolism*; D020866:omega-Conotoxin GVIA
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002395:Catecholamines; D018722:Nicotinic Agonists; D010455:Peptides; D011978:Receptors, Nicotinic; D009538:Nicotine; D020866:omega-Conotoxin GVIA; D000109:Acetylcholine; D011188:Potassium; D009638:Norepinephrine; D004837:Epinephrine