Rapid polyphosphoinositide decrease is an early event in the steroidogenic response of bovine adrenocortical fasciculata cells to angiotensin II

Addition of angiotensin II (0.3 microM) to bovine adrenal fasciculata cell suspensions prelabeled with 32P] induced a rapid (15 seconds) and marked decrease of the radioactivity from phosphatidylinositol 4,5-biphosphate (62%) and phosphatidylinositol 4-monophosphate (35%). This effect was concentration-dependent and specifically inhibited in the presence of (Sar1-Ala8)-angiotensin II; it was also completely prevented in the absence of extracellular calcium. The present data appear to illustrate the earliest biological response detectable in bovine fasciculata cells under angiotensin II challenge.