EFFECTS OF NITROGLYCERIN ON THE CIRCULATORY-SYSTEM, MYOCARDIAL DYNAMICS AND LEFT-VENTRICULAR OXYGEN-CONSUMPTION IN THE ANESTHETIZED BEAGLE-DOG

Effects of nitroglycerin (3.0; 6.3 and 10.0/μg/kg i.v.) on the circulatory system, myocardial dynamics, and left ventricular oxygen consumption have been investigated in 10 pure-bred beagle dogs by means of thermodilution and catheter techniques following sodium pentobarbital anesthesia. Nitroglycerin, as a rule, induced its maximum effects one minute after injection and was active-mostly dose-dependent-for 3 to 5 minutes. Some effects, however, persisted for about 20 minutes. Mean arterial blood pressure (MAP) in the femoral artery together with total peripheral resistance (TPR) were reduced. Heart rate (HR) rose slightly. Positive inotropy was evident from a pronounced increase of dP/dtmax and from an elevation of the contractile parameters VCE and Vpm, as well as from a reduction of t-dP/dt, while the ejection time (ET) was shortened. Respiration rate simultaneously increased for some minutes. Left ventricular systolic pressure (LVP) and enddiastolic pressure (LVEDP) were reduced with a concomitant lasting diminution of ventricular endsystolic volume (LVESV). Stroke volume index and cardiac output index (SVI and COI) showed a persistent decrease; furthermore, cardiac work (CW) was reduced. Left ventricular oxygen consumption (MVO2) was diminished for about 15 minutes following an initial increase within the first minute after nitroglycerin injection. The hemodynamic alterations induced by nitroglycerin are discussed. © 1979 Dr. Dietrich Steinkopff Verlag.