AJP - Endocrinology and Metabolism, Vol 247, Issue 5 645-E650, Copyright © 1984 by American Physiological Society
Dihydropyridine calcium agonist and antagonist effects on aldosterone secretion
K. Kojima, I. Kojima and H. Rasmussen
The effects of the dihydropyridine calcium antagonists nimodipine,
nitrendipine, and nisoldipine were studied on K+-induced and angiotensin II
(ANG II)-induced aldosterone secretion from isolated calf adrenal
glomerulosa cells. These drugs were more effective inhibitors of K+-induced
secretion than ANG II-induced secretion. However, when the ANG II-induced
release of intracellular calcium was blocked by prior treatment of cells
with dantrolene, then nitrendipine was equally as effective in blocking ANG
II- as K+-induced secretion. On the other hand, the dihydropyridine
agonist, BAY K8644, was found to enhance K+-induced secretion to a greater
extent than ANG II-induced secretion when the latter was studied in either
the absence or presence of dantrolene. It is concluded that K+ and ANG II
mobilize calcium from different sources for stimulus-response coupling in
these cells and that there is no difference in the sensitivity to
nitrendipine of the plasma membrane calcium channels operated by these two
different agonists.
