EFFECTS OF NITRENDIPINE ON CORONARY FLOW AND MYOCARDIAL OXYGEN AND CARBON DIOXIDE METABOLISM IN DOGS

In the present study, the coronary sinus blood flow, oxygen and carbon dioxide content, rate of myocardial oxygen uptake, carbon dioxide production and myocardial oxgyen consumption were measured before and 1, 3, 5, 10, 20, 30, 60, 00, 120, 150, 180 min after intravenous injection of nitrendipine 20 μg/kg. The coronary sinus blood flow and oxygen content were significantly increased while the systemic blood presure lowered. Five min after drug administration, MBP decreased from 14.4±2 kPa(108±16/102±15 mmHg) to 7.7±20/7.25±2.0 kPa (58±16/54±15 mmHg); coronary sinus blood flow incresed from 47±4.0 ml/min/100 g to 79.0±8.0 ml/min/100 g; coronary sinus oxygen content incresed from 8.7±0.6 ml% to 13.9±0.70 ml%; the rate of myocardial oxgyen uptake, myocardial oxgyen consumption and rate of carbon dioxide production decreased from 51.8±3% to 23.9±2%; from 4.45±0.4 ml/min/100 g to 3.0±0.4 ml/min/100 g; and from 55.6±7% to 37.7±6%, respectively. The duration of effects lasted more than 3 h. These results indicate that nitrendipine may have beneficial effects not only for hypertension but also for ischemic heart disease.