Angiotensin II stimulates inositol phosphate formation in rat anterior pituitary glands.

The effect of angiotensin II (AII) on polyphosphoinositide (PPI) turnover at the pituitary was studied. When [3H]inositol-prelabelled rat anterior hemipituitaries were incubated with AII (10 microM) for 30 min in the presence of Li+ (10 mM), the production of IP, IP2 and IP3 were increased to 182, 199 and 158% of paired control values. Time course studies showed that the stimulation of IP3 formation by AII was significant after 2 min incubation and preceded the accumulation of the other inositol phosphates. The specificity of the AII effect was confirmed by inhibition with the specific AII antagonist, saralasin. These findings suggest that AII action at the anterior pituitary can be mediated via the early hydrolysis of PPI.