Cyclooxygenase-dependent mediators of renal hemodynamic function in female rats

Previous studies have revealed a sex-dependent difference in response to cyclooxygenase inhibition in anesthetized male and female rats. Female rats have shown an unexpected vasodilation in response to prostaglandin (PG) inhibition. The present studies were designed to further investigate the sex-dependent role of the PG system in the control of normal renal hemodynamics in female Munich-Wistar rats. Renal hemodynamic studies were performed on anesthetized female rats before and during acute cyclooxygenase inhibition using a variety of protocols. One group underwent subacute unilateral renal denervation. A separate group was chronically catheterized and plasma catecholamines were measured during the awake state and then after anesthesia under the euvolemic protocol. Another group was administered the angiotensin II blocker, saralasin, before and during cyclooxygenase inhibition. In a final group, flow to the distal nephron was interrupted via placement of a wax block into the late proximal tubule to determine the role of distal nephron flow and tubuloglomerular feedback in the glomerular response to cyclooxygenase inhibition. It was determined that neither the wax block nor saralasin administration attenuated the vasodilatory response observed in normal female rats due to cyclooxygenase inhibition; however, subacute unilateral renal denervation completely blocked the vasodilatory response to PG inhibition in these female Munich-Wistar rats. Plasma catecholamines were found to be similar whether awake or under anesthesia. These studies indicate the importance of the adrenergic system in modulating PG production in the acutely anesthetized intact female rat.