Dose-dependent effects of angiotensin II, acetylcholine and vasopressin on the cytosolic concentration of Ca2+ in suspension primary cultures of zona fasciculata/reticularis cells from bovine adrenal cortex.
The effects of angiotensin II (AII), acetylcholine and vasopressin on the intracellular concentration of Ca2+ have been little studied in adrenocortical cells from the zona fasciculata/reticularis (ZFR). Primary cultures of bovine ZFR cells maintained in suspension cultured for 72 h produce cortisol in response to AII (0.1 microM), acetylcholine (0.1 mM) and vasopressin (1 microM). This response is accompanied by a breakdown of membrane phosphoinositides from [3H]inositol-prelabelled cells. Using cells loaded with the Ca2+ indicator fura-2, the intracellular concentration of Ca2+ was measured in response to increasing doses of all three agonists and found to increase in a graded fashion in each case. The basal intracellular concentration of Ca2+ was 75 +/- 3 nM (mean +/- S.E.M., n = 52), rising to a maximum 1.82 +/- 0.14-fold (n = 6) for AII (0.1 microM), 1.35 +/- 0.05-fold (n = 7) for acetylcholine (0.1 mM) and 1.27 +/- 0.10-fold (n = 6) for vasopressin (1 microM). In the case of AII and acetylcholine, agonists were added sequentially in medium of normal extracellular Ca2+ concentration (1.2 mM) or in medium in which the Ca2+ concentration was buffered to approximate to the intracellular concentration of Ca2+ (75-100 nM). Evidence was thereby obtained that both AII and acetylcholine mobilize a common intracellular pool of Ca2+. Our findings suggest that these three agonists, all of which stimulate phospholipase C, increase intracellular Ca2+ through a mechanism which depends, at least in part, on the release of Ca2+ from a common intracellular pool.
Walker
S W
SW
University Department of Clinical Chemistry, Royal Infirmary, Edinburgh.
Strachan
M W
MW
Nicol
M
M
Williams
B C
BC
Bird
I M
IM
D000109:Acetylcholine / Q000494:pharmacology*; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D016257:Fura-2; D006854:Hydrocortisone / Q000378:metabolism; D007294:Inositol / Q000378:metabolism; D007700:Kinetics; D013050:Spectrometry, Fluorescence; D010738:Type C Phospholipases / Q000378:metabolism; D015383:Zona Fasciculata / Q000187:drug effects / Q000378:metabolism*; D015385:Zona Reticularis / Q000187:drug effects / Q000378:metabolism*
D000804:Angiotensin II; D001127:Arginine Vasopressin; D007294:Inositol; D010738:Type C Phospholipases; D000109:Acetylcholine; D002118:Calcium; D016257:Fura-2; D006854:Hydrocortisone