CARDIOVASCULAR PROFILE OF MIXIDINE FUMARATE, A COMPOUND WHICH ATTENUATES MYOCARDIAL CHRONOTROPIC RESPONSES

  • 1 January 1980
    • journal article
    • research article
    • Vol. 212  (3) , 514-518
Abstract
The effect of mixidine [MD] fumarate on myocardial chronotropic responses to various stimulants was examined. MD decreased elevated heart rate [HR] in the anesthetized dog to basal levels. It produced a dose-related decrease in HR elevated reflexly by aminophylline, by .beta.-adrenergic stimulation induced by isoproterenol [IP], by sympathetic nerve stimulation and by i.v. infusion of glucagon. MD attenuated the increase in contractile force produced by sympathetic nerve stimulation but not that induced by IP. The compound antagonized the increase in rate of isolated guinea-pig atria induced by both IP and histamine. In the conscious dog, MD caused no decrease in resting HR, mean arterial pressure and cardiac output. It reduced atropine-induced sinus tachycardia as well as that induced by treadmill exercise. Experiments in the dog heart-lung preparation indicated that attenuation of an epinephrine-induced sinus tachycardia led to a decrease in myocardial O2 consumption and an increase in myocardial efficiency. MD apparently induces an antichronotropic activity by a direct effect on the sinoatrial node and by attenuating sympathetic nervous system input to the heart.

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