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Calcium modulation of the renin-aldosterone axis
L Porter1, P R Conlin, J Scott
1Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
Journal of Endocrinological Investigation
|April 9, 1999
Summary
Physiologic increases in extracellular calcium blunt the diurnal decline in plasma renin activity (PRA) and aldosterone. Calcium directly impacts PRA, while aldosterone
Area of Science:
- Endocrinology
- Nephrology
- Calcium Homeostasis
Background:
- Extracellular calcium concentration influences hormone secretion.
- In vitro studies show juxtaglomerular cells secrete renin inversely to calcium.
- Human in vivo data on calcium's effect on renin secretion is limited.
Purpose of the Study:
- Investigate the effects of physiological calcium level changes on renin and aldosterone secretion in humans.
- Clarify the role of extracellular calcium in regulating the renin-angiotensin-aldosterone system (RAAS).
Main Methods:
- Seven healthy men received infusions of dextrose, disodium edetate (EDTA), and calcium gluconate.
- Serum ionized calcium, ACTH, plasma renin activity (PRA), and aldosterone were measured.
- Infusions were repeated with dexamethasone pre-treatment to assess hormonal mediation.
Main Results:
- Calcium infusions increased ACTH, PRA, and aldosterone levels.
- Dextrose and EDTA infusions decreased ACTH, PRA, and aldosterone.
- Dexamethasone suppressed ACTH and aldosterone response to calcium but not PRA response.
Conclusions:
- Increased physiological calcium levels attenuate the diurnal decrease in PRA and aldosterone.
- Calcium appears to directly affect PRA.
- Calcium's effect on aldosterone is mediated through ACTH.