Renal effects of cyclooxygenase inhibition in the pregnant rat.

Experiments were performed to investigate the effects of acute cyclooxygenase inhibition on renal hemodynamics in mid and late pregnant rats. In micropuncture studies in the control state, midterm pregnant rats exhibited increased single-nephron glomerular rate (SNGFR) and no change in glomerular or arterial blood pressures. In late pregnancy, SNGFR was no longer significantly elevated, glomerular pressure was similar, and arterial pressure was depressed compared with the virgin. Cyclooxygenase inhibition led to significant increases in single-nephron and whole-kidney filtration and flow in mid and late pregnant rats. This effect was also seen in the virgin control group, and all groups involved a selective renal vasodilation without change in blood pressure. In the absence of anesthesia and surgical stress, cyclooxygenase inhibition had little effect in virgin or pregnant chronically catheterized rats. These studies indicate that the cyclooxygenase-dependent arachidonic acid metabolites are not the agents directly responsible for the gestational rise in the glomerular filtration rate.