MATERIALS AND METHODS

Healthy, male rabbits weighing 2.3-2.9 kg were used. Ameroid clips were surgically placed on the ascending aorta as previously described(26). These clips slowly swell, constricting the aorta (Fig. 1A) and producing marked cardiac hypertrophy(Fig. 1B) and eventual failure.

Left ventricular pressure and peak isovolumic pressure were measured prior to removing the hearts for biochemical studies. The animals were anesthetized and the thorax was opened through a sternal-splitting incision. An 18-gauge needle attached to a Statham pressure transducer (P-23Db) was inserted into the left ventricle at the apex. Pressure was continuously recorded on a Grass multichannel polygraph. After steady-state pressures were obtained the aorta was clamped between the heart and the Ameroid clip. The vessel was totally occluded for 30-60 set and then the clamp was released. The peak systolic pressure recorded during occlusion was considered as the peak isovolumic pressure of the heart (23). Mitochondria were isolated in a 0.18 M KCl, 10 mM EDTA, 0.5 70 bovine serum albumin medium(KEA),