Plasma renin activity and kidney damage in response to acute renal ischaemia and ramipril treatment in ovariectomised and uninephrectomised rats

Abstract

The renin-angiotensin system is thought to be modulated by gonadal steroids. 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 (ACEI) on PRA are also unclear. Female Wistar rats underwent right nephrectomy, and some bilaterally ovariectomised or intact rats were also subjected to occlusion of the left renal artery for 45 min. Ramipril was given intragastrically for 2 days at a dose of 7.5 mg kg(-1). Kidneys from rats decapitated 2 days after acute renal ischaemia were histopathologically examined. Ovariectomy not only caused a decrease in PRA but also reduced the PRA response to acute renal ischaemia. In contrast, ovariectomy had a reverse effect, raising PRA activity when ramipril, an ACE inhibitor, was used to prevent excessive angiotensin II formation due to renal ischaemia. Ischaemia alone caused less damage in the rats with no ramipril treatment as compared with ramipril-treated rats. 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 acute renal ischaemia and may lead to changes in the effect of ACEI in rats.