Calcium dependence of osmolality-, potassium-, and angiotensin II-induced aldosterone secretion.
Different calcium-dependent mechanisms may be involved in mediating stimulus-induced aldosterone secretion. Using isolated perfused canine adrenal glands, we determined the effect of reductions in extracellular [Ca2+] and of infusion of a voltage-dependent calcium channel antagonist, nifedipine, on aldosterone secretion induced by decreases in osmolality, by increases in [K+], or by infusion of angiotensin II (ANG II). Aldosterone secretion was stimulated to a similar level by reducing osmolality, by increasing [K+], or by infusing ANG II. After 50 min of stimulation, lowering [Ca2+] from 1.25 to 0.10 mM caused a marked and similar inhibition of osmolality- and [K+]-induced aldosterone secretion that was significantly greater than inhibition of ANG II-induced aldosterone secretion. Similarly, nifedipine at 3.3 X 10(-8) M caused marked and similar inhibition of osmolality- and [K+]-induced aldosterone secretion that was significantly greater than the inhibition of ANG II-induced aldosterone secretion. These data demonstrate that calcium-dependent processes are involved in osmolality-, [K+]-, and ANG II-induced aldosterone secretion. However, the calcium-dependent process(es) evoked by reductions in osmolality or increases in [K+] are considerably different from that evoked by ANG II. Osmolality and potassium appear to induce aldosterone secretion primarily by activating voltage-dependent calcium channels.
Radke
K J
KJ
Department of Physiology and Biophysics, University of Tennessee, Memphis 38163.
Clendenin
R E
RE
Taylor
R E
RE
Schneider
E G
EG
D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism*; D000450:Aldosterone / Q000378:metabolism*; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D004285:Dogs; D005260:Female; D006982:Hypertonic Solutions; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D009994:Osmolar Concentration; D011188:Potassium / Q000494:pharmacology*
D006982:Hypertonic Solutions; D000804:Angiotensin II; D000450:Aldosterone; D011188:Potassium; D002118:Calcium