PLASMA-RENIN ACTIVITY AND KIDNEY DAMAGE IN RESPONSE TO ACUTE RENAL ISCHEMIA AND RAMIPRIL TREATMENT IN OVARIECTOMIZED AND UNINEPHRECTOMIZED RATS

The renin-angiotensin system is thought to be modulated by gonadal ste roids. However, it is uncertain whether gonadal steroids also modulate the changes in plasma renin activity (PRA) in response to acute renal ischaemia. The effects of angiotensin-converting enzyme inhibitors (A CEI) on PRA are also unclear. Female Wistar rats underwent right nephr ectomy, and some bilaterally ovariectomised or intact rats were also s ubjected to occlusion of the left renal artery for 45 min. Ramipril wa s given intragastrically for 2 days at a dose of 7.5 mg kg(-1). Kidney s from rats decapitated 2 days after acute renal ischaemia were histop athologically examined. Ovariectomy not only caused a decrease in PRA but also reduced the PRA response to acute renal ischaemia. In contras t, ovariectomy had a reverse effect, raising PRA activity when ramipri l, an ACE inhibitor, was used to prevent excessive angiotensin II form ation due to renal ischaemia. Ischaemia alone caused less damage in th e rats with no ramipril treatment as compared with ramipril-treated ra ts. Thus ramipril exacerbates the damaging effect of ischaemia on the kidney. Ovariectomy reduced kidney damage in the ramipril-treated rats . Gonadal steroids may have a role in modulating the PRA response to a cute renal ischaemia and may lead to changes in the effect of ACEI in rats.