Renal response to vasopressin after inhibition of prostaglandin synthesis.

The renal effects of vasopressin (VP) in water-loaded and hydropenic conscious dogs were examined with and without the previous administration of prostaglandin (PG) synthesis inhibitors (indomethacin and meclophenamate). The parameters studied were: urinary output, sodium and potassium excretion, plasma and urinary osmotic concentration, total renal blood flow, mean arterial pressure, heart rate, and the clearance and extraction ratio of p-aminohippuric acid and inulin. The infusion of VP caused antidiuresis and marked saluresis during water diuresis, whereas it was found to be diuretic and saluretic in hydropenic animals. Inhibition of PG synthesis greatly enhanced the antidiuretic activity of VP and abolished its saluretic and diuretic actions. Changes in renal water and solute excretion and changes in the hemodynamic parameters are uncorrelated. It is concluded that intrarenal PGs may play an important role in modulating the renal action of VP.