Background/aims: The role of endothelin (ET) in cardiovascular remodeling was investigated by treating uninephrectomized spontaneously hypertensive rats of the stroke-prone strain (UNX-SHRsp) on normal- or high (3%)-salt diet with the selective ET(A) receptor blocker LU 135252.
Methods: SHRsp on normal or high salt were sham-operated (n = 10/11) or UNX; UNX received no treatment (n = 10/15) or 100 mg/kg body weight LU 135252 (n = 10/10). Systolic blood pressure (BP) was measured weekly. After perfusion fixation the heart and the aorta were analyzed using quantitative morphological and stereological techniques.
Results: No effect was seen in normal-salt groups. In high-salt animals UNX caused left ventricular (LV) hypertrophy which was prevented by LU 135252 (p < 0.001). LU 135252 only lowered BP during the last 2 weeks of the 12-week experiment. UNX showed hypertrophic remodeling of intramyocardial arterioles. Treatment with LU 135252 caused lower wall:lumen ratio and wall thickness of LV intramyocardial arterioles (p < 0.01). In the descending thoracic aorta UNX caused thickening of the media. The media area and the wall:lumen ratio were lower in UNX + LU 135252 as compared to untreated UNX (p < 0.01 and p < 0.05, respectively).
Conclusion: In SHRsp UNX causes hypertrophic cardiovascular remodeling only in the presence of salt loading. These effects are largely BP-independent and prevented by ET(A) receptor blockade.
(c) 2007 S. Karger AG, Basel.