Nifedipine blocks ACTH and cortisol release in man.
1. The present study investigated the effect of prior administration of nifedipine on AVP-induced ACTH release in seven normal volunteers. Three protocols were used: 20 mg oral nifedipine; 0.14 pressor units intramuscular (i.m.) per kg bodyweight aqueous AVP; oral nifedipine plus i.m. AVP 90 min later. Plasma ACTH and cortisol were measured at intervals for 2.5 h during each test. 2. The mean peak plasma ACTH and cortisol levels and the mean peak changes from basal in these levels were significantly lower in the nifedipine/AVP test than in the AVP alone test. The integrated area under the cortisol time curve was significantly lower for the nifedipine/AVP test than that for the AVP test alone. Nifedipine alone caused no changes in ACTH or cortisol. 3. Acute administration of oral nifedipine caused an inhibition of AVP-stimulated ACTH and cortisol release in normal humans. This effect may be due to blockade of plasma membrane calcium channels normally activated during AVP stimulation of pituitary corticotrophs.
Jackson
R V
RV
University Department of Medicine, Greenslopes Hospital, Brisbane, Queensland, Australia.
Jackson
A J
AJ
Grice
J E
JE
Vella
R D
RD
D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000328:Adult; D001127:Arginine Vasopressin / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009543:Nifedipine / Q000494:pharmacology*
D001127:Arginine Vasopressin; D000324:Adrenocorticotropic Hormone; D009543:Nifedipine; D006854:Hydrocortisone