The effects of extracellular K+ and angiotensin II on cytosolic Ca++ and steroidogenesis in adrenal glomerulosa cells.
We evaluated changes in cytosolic calcium concentration (Ca++) and steroidogenesis in rat adrenal glomerulosa cells (GC) stimulated with potassium (K+) or angiotensin II (AII). Cytosolic Ca++ concentration was determined using the Ca++-sensitive, fluorescent dye QUIN 2. Raising extracellular K+ increased cytosolic Ca++ from 267 +/- 23 nM at 3.7 mM K+ to a maximum of 377 +/- 40 nM at 8.7 mM K+ (p less than 0.01, N = 23). AII also increased cytosolic Ca++ from 238 +/- 20 nM to a maximum of 427 +/- 42 nM at 10(-7) M (p less than 0.01, N = 16). In parallel studies, K+ and AII stimulated aldosterone secretion from QUIN 2-loaded GC at concentrations similar to those which raised cytosolic Ca++. QUIN 2-loaded cells were as responsive steroidogenically as unloaded cells and showed trypan blue exclusion of 98% suggesting that QUIN 2 did not compromise cellular viability. These results provide direct support for a role of cytosolic Ca++ as a second messenger during stimulation of aldosterone secretion by both K+ and AII.
D000302:Adrenal Cortex / Q000187:drug effects* / Q000378:metabolism; D000450:Aldosterone / Q000096:biosynthesis; D000634:Aminoquinolines / Q000378:metabolism; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology*; D051381:Rats
D000634:Aminoquinolines; D005456:Fluorescent Dyes; D000804:Angiotensin II; D000450:Aldosterone; C035738:Quin2-acetoxymethyl ester; D011188:Potassium; D002118:Calcium