Comparable effects of angiotensin II and converting enzyme blockade on hemodynamics and cardiac hypertrophy in spontaneously hypertensive rats.

Angiotensin-converting enzyme inhibitors may regress left ventricular hypertrophy (LVH) without decreasing blood pressure (BP). The aim of the present study was to compare the effects of low and high doses of lisinopril and the angiotensin II receptor antagonist TCV116 (TCV) on LVH and hemodynamics in spontaneously hypertensive rats (SHR). Lisinopril (0.5 and 3 mg/kg per day) and TCV (0.3 mg/kg per day) were given to 8-week-old male SHR daily for 2 weeks. Untreated SHR and Wistar-Kyoto rats (WKY) served as controls. Untreated SHR had a greater left ventricular (LV) weight than WKY (p < 0.01). Lisinopril (3 mg/kg per day) decreased both LV weight and BP. Lisinopril (0.5 mg/kg per day) significantly decreased LV weight, but not BP. In contrast, although TCV significantly decreased BP, LVH was not suppressed. Renal blood flow (RBF) in untreated SHR was less than that in WKY (p < 0.05), but was increased with either lisinopril (3 mg/kg per day)-treated rats (p< 0.05). These findings suggest that factors other than afterload reduction play a role in the regression of LVH with lisinopril, whereas a longer duration of treatment and/or a higher dose may be necessary with TCV. Despite the decrease in BP, TCV normalized RBF in SHR, perhaps due to the blockade of renal angiotensin II.