STUDIES OF HORMONE-SENSITIVE AND HORMONE-INSENSITIVE POOLS OF PHOSPHOINOSITIDES IN CULTURED BOVINE ZONA-FASCICULATA RETICULARIS CELLS - EVIDENCE THAT ACETYLCHOLINE AND ANGIOTENSIN-II STIMULATE THE BREAKDOWN OF A COMMON POOL OF PHOSPHOINOSITIDES

The effects of acetylcholine (ACh) and manganese pre-incubation on angiotensin II (AII)-stimulated incorporation of [H-3]inositol into phosphoinositide, phosphoinositol and free inositol fractions of adrenocortical cells isolated from the bovine zona fasciculata/reticularis (zfr) were investigated. In cells pre-labelled for 6 hr with [H-3]inositol, ACh and AII stimulated the incorporation of cytosolic [H-3]inositol into a common hormone-sensitive pool of phosphoinositides, which was distinct from the non-hormone-sensitive pool labelled in the presence of manganese. Regression analysis of the cortisol versus [H-3]inositol headgroup responses for both AII (10(-11)-10(-7) M) and ACh (10(-9)-10(-3) M) showed that the gradients of these responses were not significantly different. These data provide strong evidence that in cultured bovine zfr cells, ACh and AII stimulate the breakdown and resynthesis of a common pool of phosphoinositides.