Cardiovascular effects of S 9490-3, a new converting enzyme inhibitor: a computerized study in conscious...

The acute cardiovascular effects of S 9490-3, a new angiotensin converting enzyme (ACE) inhibitor, were studied by means of a computerized analysis of the intra-aortic blood pressure (BP), recorded continuously for 48 h in conscious, unrestrained, adult spontaneously hypertensive rats (SHR). The first 24-h recording period was used as a control. On the second day, the rats received a single intravenous (i.v.) injection of S 9490-3 (0.2 mg/kg) at 11 a.m. followed by another 2 mg/kg i.v. injection at 3 p.m. Cardiovascular activity was studied up to 8 a.m. the next day. No significant cardiovascular effects appeared after the 0.2 mg/kg dose, whereas the 2 mg/kg dose induced a rapid fall in systolic and diastolic BP, which remained significant for about 11 h. This BP decrease was not associated with any elevation in heart rate, but with a short lasting increase in dP/dt max. These results are in good agreement with those already obtained with S 9490-3 in various experimental conditions. They suggest that long-term recordings of intra-arterial BP in freely moving rats is of value in the study of drugs which act on the cardiovascular system.