Angiotensin-converting enzyme (ACE) inhibitors appear to correct many of the abnormalities associated with the vascular dysfunction found in diabetic patients. In this respect, quinapril is a unique ACE inhibitor with multiple protective effects. The present study was carried out to investigate the effect of intraperitoneal administration of quinapril on the aortic reactivity of streptozotocin (STZ)-diabetic rats. For this purpose, male Wistar rats received one injection of streptozotocin (STZ), 60 mg/kg, to induce diabetes. Three days after STZ injection, rats were treated with quinapril (2 mg/kg/day) for 4 weeks, after that aortic reactivity to vasoactive agents were compared with those of untreated diabetic rats or non-diabetic control rats. For this purpose, contractile response to phenylephrine (PE) was obtained from aortic rings. Concentration-response curves from quinapril-treated diabetic rats to PE in the presence and absence of endothelium were attenuated as compared to vehicle-treated diabetics. Therefore, the 4-week treatment of diabetic rats with quinapril could prevent the functional changes in vascular reactivity in diabetic rats
