title: Effects of dihydropyridines on aldosterone secretion in adrenal capsule preparations from pregnant rats.
abstract: The primary aim of this study was to determine when sensitivity in the aldosterone response to extracellular potassium (K+) decreases during pregnancy. Second, it tested the hypothesis that calcium channel alterations occur in the adrenal cortex during pregnancy. The decreased sensitivity to K+, observed at 22 days of gestation, was not evident at 15 days and between 18 and 36 h postpartum. Increases in extracellular calcium concentration heightened sensitivity to K+ in adrenal capsule preparations derived from nonpregnant rats but had no effect in pregnant animals. The influence of nifedipine and BAY K 8644 (blocker and activator, respectively, of voltage-operated calcium channels) on the aldosterone response to K+ and to adrenocorticotropic hormone (ACTH) was studied. Sensitivity to K+ in nonpregnant rats decreased in the presence of nifedipine and became similar to that in pregnant rats. Responses to ACTH were not affected by nifedipine. BAY K 8644 produced a larger increase in sensitivity in adrenal capsule preparations from pregnant than from nonpregnant rats, leading to superposition of the two dose-response curves to K+. These results indicate that voltage-operated calcium channels involved in aldosterone secretion are functionally impaired during pregnancy.
authors.affiliation: Research Center, Sainte-Justine's Hospital, Montréal, Québec, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Brochu
authors.forename: S
authors.initials: S
authors.lastname: Picard
authors.forename: S
authors.initials: S
authors.lastname: Jodoin
authors.forename: J
authors.initials: J
authors.lastname: St-Louis
mesh_terms: 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*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000450:Aldosterone / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004095:Dihydropyridines / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D009994:Osmolar Concentration; D011188:Potassium / Q000494:pharmacology; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004095:Dihydropyridines; D000450:Aldosterone; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000324:Adrenocorticotropic Hormone; D011188:Potassium; D002118:Calcium