Prostaglandin E2 and F2 alpha reduces urea reabsorption from the rat collecting duct.

The present study examines the possibility that prostaglandins affect the renal tubular handling of urea. Meclofenamate (1 mg.kg-1.h-1), an inhibitor of prostaglandin synthesis, decreased fractional urea clearance from 86 to 67%, increased urine osmolality, and decreased the fractional excretion of water in rats undergoing a hypertonic sodium chloride diuresis. The percentage of [14C]urea microinjected into distal convoluted tubules that was recovered in urine fell from 75 to 64% (P less than 0.01) after meclofenamate. The fraction of injected urea excreted like inulin (direct recovery) was reduced from 20 to 8% (P less than 0.0001) by meclofenamate. Addition of PGE2 (1.2 or 89 pmol) or PGF2 alpha (1.4 pmol) to the microinjectate returned the urinary recovery of the microinjected [14C]urea to the control level, but PGA2 (3 pmol) did not. Direct urea recovery was doubled by PGE2 or PGF2 alpha. These results indicate that prostaglandin E2 and F2 alpha inhibit the reabsorption of urea in the collecting duct. Prostaglandins may participate in the renal concentrating mechanism by altering the inner medullary influx of urea.