A component of the catecholamine secretory response in the bovine adrenal gland is resistant to dihydropyridines and omega-conotoxin.
Acetylcholine (ACh, 100 microM)-evoked catecholamine release from perfused bovine adrenal glands was unaffected by CTX (0.3 microM) and depressed 70% by nisoldipine (1 microM). Combined CTX plus nisoldipine did not inhibit further the secretory response K+ (150 mM)-evoked secretion was diminished 30% by CTX and 20% by nisoldipine. Combined CTX plus nisoldipine inhibited secretion by 35%. Cd2+ blocked the K(+)-evoked secretory response by over 90%. Bay K 8644 (1 microM) enhanced the basal output of catecholamines and clearly potentiated the secretory responses to mild concentrations of ACh (3 microM) or K+ (17.7 mM). The results suggest that in addition to CTX- and DHP-sensitive Ca2+ channels, a third Ca2+ pathway might contribute to the entry of external Ca2+ into chromaffin cells necessary to trigger the exocytotic catecholamine release response in the bovine adrenal gland.
Jiménez
R R
RR
Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, Spain.
López
M G
MG
Sancho
C
C
Maroto
R
R
García
A G
AG
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000109:Acetylcholine / Q000494:pharmacology; D000311:Adrenal Glands / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000502:physiology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D004095:Dihydropyridines / Q000494:pharmacology*; D066298:In Vitro Techniques; D008978:Mollusk Venoms / Q000494:pharmacology; D015737:Nisoldipine / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D012636:Secretory Rate / Q000187:drug effects; D020960:omega-Conotoxins
D002121:Calcium Channel Blockers; D002395:Catecholamines; D004095:Dihydropyridines; D008978:Mollusk Venoms; D010456:Peptides, Cyclic; D020960:omega-Conotoxins; C053423:Conus magus toxin; D015737:Nisoldipine; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000109:Acetylcholine; D011188:Potassium; D002118:Calcium