Different sensitivities to dihydropyridines of catecholamine release from cat and ox adrenals.
Catecholamine release evoked by quick pulses of Ca2+ (2.5 mM) given sequentially at 30 min intervals to cat and ox adrenal glands perfused continuously with Ca2+ free Krebs-Tris solutions containing 35 or 118 mM K+, was studied. In the feline, the secretory response was highly sensitive to various dihydropyridine (DHP) derivatives. For instance, secretion was completely blocked by nM concentrations of (+)isradipine (IC50 between 3 and 4 nM) and markedly potentiated by (-)Bay-K-8644. In contrast, the bovine secretory responses were resistant to blockade by nitrendipine or (+)isradipine, as well as to potentiation by Bay-K-8644, even at microM concentrations. From these experiments, it seems clear that distinct subtypes of Ca2+ channels might mediate a similar secretory response in ox and cat adrenal chromaffin cells, at least in the present experimental conditions.
Gandía
L
L
Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Facultad de Medicina, Spain.
Michelena
P
P
de Pascual
R
R
López
M G
MG
García
A G
AG
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002120:Calcium Channel Agonists / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism*; D002415:Cats; D002417:Cattle; D004095:Dihydropyridines / Q000494:pharmacology*; D066298:In Vitro Techniques; D017275:Isradipine; D008297:Male; D009568:Nitrendipine / Q000494:pharmacology; D010477:Perfusion; D013045:Species Specificity
D002120:Calcium Channel Agonists; D002121:Calcium Channel Blockers; D002395:Catecholamines; D004095:Dihydropyridines; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D009568:Nitrendipine; D002118:Calcium; D017275:Isradipine