Effect of propranolol on regional myocardial function in anesthetized open-chest dogs with myocardial ischemia

Effects of propranolol on ischemic segmental function were studied in anesthetized open-chest dogs. Two segment-length gauges were used for measuring the regional myocardial function: one was sutured on to the left ventricular surface perfused by the anterior descending coronary artery (ischemic zone) and the other was on to that perfused by the circumflex coronary artery (normal zone). A bolus of propranolol (0.5 mg/kg) was injected into the right femoral vein. Five min later, the left anterior descending coronary artery (LAD) was completely occluded for one mine and thereafter released. Then a second coronary occlusion for 20 min was performed; an interval of 20 min was allowed between two occlusions. Propranolol, in the ischemic segment, apparently decreased the extent of paradoxical lengthening in the late systole following one min LAD occlusion, and facilitated improvement of segmental function after release of the occlusion. Moreover, the extent of abnormal stretching induced by 20 min occlusion during early systole, was also reduced by propranolol pretreatment. In contrast, compensatory increase in shortening by the normal segment was disturbed by propranolol. These results suggest that propranolol might exert a favourable influence on the segmental myocardial function during either transient or maintained myocardial ischemia.</p

Effect of Ethanol on Hemodynamics of the Anesthetized Open-Chest Dog

Hemodynamic effects caused by ethanol infusion systemically in dose of 75 mg per kilogram per minute for 20 minutes have been studied in anesthetized open-cest dogs, and following results were obtained. Cardiac output, stroke volume and heart rate did not change and total peripheral resistance decreased with a fall in systemic blood pressure. Reduction in coronary vascular resistance, as same as a fall in total peripheral resistance, was observed with no change in coronary blood flow. Diminished left ventricular function, manifested as rise in end-diastolic pressure and a decline in deflection of segmental contraction curve of left ventricle, was observed in most cases. Isoproterenol (0.1μg/kg) injected intravenously after the in fusion of ethanol, produced a rise in systolic blood pressure and an elevation in left ventricular end-diastolic pressure (LVEDP), while a fall in blood pressure and a decline in LVEDP were caused with the intravenous injection of isoproterenol before the infusion of ethanol. Effects of isoproterenol on heart rate and cardiac output after the infusion of ethanol gave no essential change when compaired with those obtained without ethanol infusion. It is concluded that ethanol dilates both of coronary and systemic arteries with depression of left ventricular function, and makes a remarkable rise in left ventricular work when a positive inotropic stimulant such as isoproterenol was given, though an increased cardiac output caused by the stimulant was not influenced with ethanol essentially

Hemodynamic Effects of Three Kinds of Beta-Adrenergic Blockade (Alprenolol, Propranolol and Practolol) -experimental study-

Effects of alprenolol, propranolol and practolol on hemodynamics were studied in open-chest anesthetized dogs, and following results were obtained; Coronary blood flow was decreased accompanied with a rise in coronary vascular resistance following the administiation of the drug. Cardiac output and heart rate were decreased, and total peripheral resistance was elevated significantly. Practolol produced lesser changes in coronary and systemic hemodynamics than alprenolol or propranolol; especially lesser elevation in total peripheral resistance and smaller decrease in maximun blood flow of aorta