Abstract
The depressant effect of reserpine on the spontaneous contraction and transmembrane potentials of the isolated atrial preparation of rabbit has been described in detail in the previous reports (1-4). A rise instead of fall in the blood pressure due to reserpine, the reserpine reversal, was demonstrated in the dog and cat pretreated with monoamine oxidase inhibitors (5, 6). Shore and Brodie (7) found that administration of reserpine to rabbits pretreated with iproniazid resulted in the sympathetic excitement. However, Eltherington and Horita (6) observed no sign of the reserpine reversal after amphetamine in mice. Shimamoto and Torii (8) observed that pretreatment of rabbits with iproniazid reversed the response of the blood pressure and the behavior to the intravenous injection of reserpine. Toda (9) of this laboratory observed that the application of monoamine oxidase inhibitors to the isolated rabbit atrium did not reverse, but delayed onset of the effect of reserpine on the atrial transmembrane potential.
Recently, Goldberg and Shideman (10) have shown that the intraperitoneal injection of a monoamine oxidase inhibitor, SKF-385, depletes the myocardial noradrenaline in cats, and conversely, accumulates it in rats. Matsuo (11). of this laboratory has shown that the application of SKF-385 to the isolated atrium of rabbit does not produce significant changes in the noradrenaline content of the atria. Pepeu et al. (12) demonstrated that the pretreatment of the guinea-pig atrium with iproniazid prevented the spontaneous depletion of noradrenaline from this tissue, but that with PIH did not so.
To elucidate the mechanism of the reserpine reversal on the spontaneous contraction of the isolated atrial preparation of rabbits, the effects of the monoamine oxidase inhibitors on the depressant action of reserpine were studied.
