Effects of Osmolality on the Interaction Between Vasopressin and Prostaglandins in Rat Renal Papillary Collecting Tubule Cells in Culture

The effect of environmental tonicity on the interaction between arginine vasopressin (AVP) and prostaglandin (PG) E in the production of adenosine-3’,5’-cyclic monophosphate (cAMP) was studied in cultured rat renal papillary collecting tubule cells. Both AVP and PGE2 stimulated intracellular cAMP accumulation in a dose-dependent manner in an isotonic medium of 300 mOsm/kg H2O in the presence of a phosphodiesterase inhibitor. Environmental tonicity modulated the effect of AVP, PGE, or of both, on cellular cAMP production. The hypertonic medium with 1,800 mOsm/kg H2O enhanced the effect of 1×10-9 M AVP on the cellular cAMP production 1.6-fold, but markedly reduced the effect of 2×10-8 MPGE1 or PGE2 to one-sixth or one-third of that in the isotonic medium. The inhibitory effect of PGE1 and PGE2 on the action of AVP was not shown in the isotonic medium, but was seen in the hypertonic medium of 1,800 mOsm/kg H2O. Synthesis of[3H]PGE2 was enhanced by hypertonicity, but not by AVP, when [3H]arachidonic acid was incorporated in the medium. The results indicate that an environmental tonicity is an important factor in modulating the effect of PGE1 or PGE2 on AVP-mediated cAMP production in renal papillary collecting tubule cells.