The cardiovascular effects of oleandrin in the dog

Abstract

The effects of oleandrin, a cardiac glycoside, were studied on a number of hemodynamic parameters and on left ventricular contractility in five groups of morphine-chloralose anesthetized dogs with a "normal" heart and intact circulation. Three dosages of oleandrin were used; 0.01 mg/kg in Group I; 0.02 mg/kg in Group II with the heart rate kept constant by pacing; 0.02 mg/kg in Group II A with a spontaneous heart rate; and 0.05 mg/kg in Group III. The dogs in Group IV were vagotomized before 0.02 mg/kg of oleandrin injection and propranolol, a 6 - adrenergic receptor antagonist was given in Group V before the parenteral administration of 0.02 mg/kg of the oleander glycoside. In general, the maximum response to oleandrin was recorded between 30 and 60 minutes after its injection. There was no obvious linear relationship between the hemodynamic changes induced by the drug and the dose administered except that the effects were more consistent with the highest dose and the variability was the least in Group III. There was no significant change in heart rate after oleandrinwith any amount of the drug, although a trend to reduce the frequency of contraction was seen with the highest dose. Left ventricular peak pressure, aortic systolic and mean pressures increased significantly after oleandrin in Group III with no significant change in either left ventricular end-diastolic or aortic diastolic pressures. Cardiac output was significantly reduced in Groups II and III and the decrease was maximal 15 minutes after injection of the glycoside. The response in cardiac output was different in Groups IV and V, inasmuch as there was no change in CO after 0.02 mg/kg of oleandrin in the vagotomized dogs (Group IV) while the cardiac output increased in response to the glycoside in the propranolol treated dogs of Group V.