Captopril reduces left ventricular enlargement induced by chronic volume overload.

The effect of captopril treatment on left ventricular (LV) function, mass, and volume during chronic volume overload induced by production of aortic insufficiency (AI) was studied. AI was caused by mechanical disruption of the aortic valve in 175- to 225-g male Sprague-Dawley rats. At 24 h after surgery, AI and sham-operated rats were divided into control and captopril treatment (2 g/l drinking water) groups. After 2 mo of treatment, hemodynamics were measured in open-chest rats, and the LV pressure-volume relation was determined ex vivo. Compared with sham-operated rats, in the untreated AI rats, aortic pulse pressure was increased nearly 100%, LV end-diastolic pressure was 10 +/- 1 vs 3 +/- 1 mmHg, and LV end-diastolic volume was 1.25 +/- 0.07 vs 0.36 +/- 0.03 ml. LV weight was increased 43% and the LV pressure-volume relation was shifted rightward by AI. LV systolic and diastolic wall stress were increased in rats with AI. Peak LV pressure during aortic occlusion was decreased in AI rats, however, peak wall stress during aortic occlusion was not different compared with sham-operated rats. Captopril treatment decreased aortic pulse pressure and LV systolic pressure. Both LV weight and LV end-diastolic volume measured from the ex vivo pressure-volume relation at LV end-diastolic pressure were increased by 33% in untreated AI rats compared with captopril-treated AI rats. Captopril treatment of AI rats shifted the LV pressure-volume to the left compared with untreated rats. LV pressure and wall stress during aortic occlusion were not changed in captopril-treated AI rats.(ABSTRACT TRUNCATED AT 250 WORDS)