Effects of angiotensin-II on inositol phosphate accumulation and calcium influx in bovine adrenal and Y-1 tumor adrenal cells.

The present study compared the action of angiotensin II (A-II) in bovine adrenal fasciculata cells (BA) and Y-1 adrenal tumor cells which are sensitive and resistant respectively to its steroidogenic effect. In both models, A-II induced a time and dose-dependent inositol phosphate (Ins-Ps) accumulation and calcium influx. However, in Y-1 cells the Ins-Ps production was low and only Ins-P1 and Ins-P2 were accumulated. The calcium influx in BA cells was observed after 15 seconds and remained linear as long as the hormone was present, whereas in Y-1 cells calcium influx started prior to 15 seconds and reverted to basal values after 45 seconds. The effects of A-II on both cell types were specific since they were blocked by A-II antagonists. Taken together these results demonstrate the presence of functional A-II receptors in both cell types which are coupled to the two main intracellular messenger systems. Thus, the A-II steroidogenic refractoriness of Y-1 cells is probably related to some alteration(s) located beyond the calcium and/or protein kinase C A-II-messenger system.