Differential effects of losartan and doxazosin on vascular function in senescent spontaneously hypertensive rats

We evaluated the effects of treatment for 12 weeks with 10 mg/kg/day of eit her losartan or doxazosin on vascular function in senescent spontaneous hyp ertensive rats (SHR). Both doxazosin and losartan reduced blood pressure, a lthough the former was more effective. In contrast, both drugs reduced rela tive aortic weight and increased plasma nitrates to a similar extent. Losar tan, but not doxazosin, increased the magnitude of the response to acetylch oline (10(-9) to 10(-5) mol/L). Both treatments increased relaxations to so dium nitroprusside (10(-10) to 10(-6) mol/L). These data show that losartan may possess advantages over doxazosin in improving vascular function in se nescent SHR. This report emphasizes the importance of angiotensin II in vas cular function alterations induced by aging in SHR. (C) 1999 American Journ al of Hypertension, Ltd.