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Nifedipine blocks ACTH and cortisol release in man
R V Jackson1, A J Jackson, J E Grice
1University Department of Medicine, Greenslopes Hospital, Brisbane, Queensland, Australia.
Clinical and Experimental Pharmacology & Physiology
|April 1, 1989
Summary
Nifedipine, a calcium channel blocker, was found to inhibit arginine vasopressin (AVP)-stimulated adrenocorticotropic hormone (ACTH) and cortisol release in healthy individuals. This suggests nifedipine may block calcium channels involved in the pituitary response to AVP.
Area of Science:
- Endocrinology
- Pharmacology
- Neuroscience
Background:
- Arginine vasopressin (AVP) is a key regulator of the hypothalamic-pituitary-adrenal (HPA) axis.
- ACTH and cortisol are critical hormones involved in the stress response.
- Calcium influx is essential for hormone release from pituitary corticotrophs.
Purpose of the Study:
- To investigate the effect of nifedipine on AVP-induced ACTH and cortisol release in humans.
- To explore the potential role of calcium channels in AVP-stimulated pituitary hormone secretion.
Main Methods:
- Seven healthy volunteers participated in the study.
- Three experimental protocols were employed: oral nifedipine, intramuscular AVP, and combined nifedipine/AVP administration.
- Plasma ACTH and cortisol levels were measured over 2.5 hours post-administration.
Main Results:
- Prior oral nifedipine administration significantly reduced peak plasma ACTH and cortisol levels induced by AVP.
- The integrated cortisol response over time was significantly lower in the nifedipine plus AVP group compared to AVP alone.
- Nifedipine administered alone did not affect ACTH or cortisol levels.
Conclusions:
- Acute oral nifedipine inhibits AVP-stimulated ACTH and cortisol release in humans.
- This inhibitory effect may be attributed to nifedipine's blockade of plasma membrane calcium channels.
- These findings highlight the role of calcium channels in mediating AVP's action on pituitary corticotrophs.