Effect of PGE2 and alpha-adrenergic agonists on AVP-dependent cAMP levels in rabbit and rat CCT.

The effect of prostaglandins and alpha-adrenergic agonists on arginine vasopressin-induced adenosine 3',5'-cyclic monophosphate (cAMP) production was investigated in microdissected rat and rabbit cortical collecting tubules (CCT) incubated in vitro. In rabbit CCT, addition to all media of a prostaglandin synthesis inhibitor increased this production; exogenous prostaglandin E2 (PGE2) induced a reproducible dose-dependent inhibition of cAMP accumulation. Maximal inhibition (mean: 57.5%) was observed with 0.3 microM PGE2, and threshold inhibition was observed with concentrations ranging from 3 to 10 nM PGE2. Inhibition of cAMP levels in rabbit CCT was also obtained with 0.3 microM PGF2 alpha (mean inhibition: 44.3%) but not with alpha-adrenergic agonists studied under the same conditions. The opposite was observed in rat CCT studied in parallel: the alpha-agonists inhibited cAMP production by up to 80%, but PGE2 had no effect.