Vasopressin Induces Breakdown of Membrane Phosphoinositides in Adrenal Glomerulosa and Fasciculata Cells

We have previously shown that vasopressin exerts a marked mitogenic effect on adrenal glomerulosa cells. In the present study, we demonstrate that vasopressin (VP) stimulates the formation of inositol monophosphate (IP), inositol diphosphate (IP2) and inositol triphosphate (IP3) in primary cultures of glomerulosa as well as fasciculata cells 5- to 8-fold over the corresponding basal values. In both cell types, the relative stimulations of IP, IP2, and IP3 formation were similar. Angiotensin II (ATII) also induced glomerulosa cells to produce a dose-dependent (up to 10-fold) increase in IP, IP2, and IP3, but had only a small effect on fasciculata cells. The dose dependencies for ATII-induced IP, IP2, and IP3 formation and aldosterone production were nearly the same. We conclude that VP- and ATII-induced formation of inositol phosphates may represent an early step in the action of these peptides on adrenal cells. However, additional elements must be involved to account for the cell specificity of VP and ATI...