[Direct cardiac effects of angiotensins I and II and 2 converting enzyme inhibitors (captopril and perindopril). Indirect demonstration of a converting enzyme in the rat heart].

In order to establish the possible existence of a cardiac converting enzyme and its role in the pathophysiology of the myocardial ischemia, the direct cardiac effects of IEC and AI or AII were studied on the isolated rat heart perfused through the left atria. Three series of seven hypertensive rats (SHR) were used. The reduction of the aortic flow (QAO) due to ischemia (produced by a left coronary artery ligation of 10 mn) was brought into line with the reduction of the coronary flow (QCORO) and the weight of the heart. This reduction was 2.06 +/- 1.8 for the control, 1.96 +/- 1.27 when captopril (CAP) (10(-5) M) was added to the perfusion liquid and 1 +/- 0.42 when perindopril (PER) (1.2 x 10(-5) M) was added to the perfusion liquid (p less than 0.05 vs CAP). Four series of 10 rat hearts (Sprague Dawley) were used to study the changes on the working heart caused by short perfusions of AI or AII (10(-7) M) in the presence of IEC or saralasin (SAR 10(-7) M). AII caused a reduction of the QCORO of 2.1 +/- 0.26 ml/mn, an increase of the QAO of 2.5 +/- 0.9 ml/mn and an increase of the heart rate (HR) of 9 +/- 3.24 beats/mn. In the presence of CAP or PER the effects of AII were the same, however in the presence of SAR these effects were prevented. AI caused a reduction of the QCOR of 2.5 +/- 0.4 ml/mn, an increase of the QAO of 2.5 +/- 0.8 ml/mn and an increase of the HR of 18 +/- 4 beats/mn.(ABSTRACT TRUNCATED AT 250 WORDS)