Ganglionic Block and Monoamine Oxidase Inhibitors

Abstract

RECENTLY, certain monoamine oxidase inhibitors have been reported to be useful in the treatment of hypertension, and some of the clinical data suggest that ganglionic blockade may be caused by such agents^1,2. To date, however, there have been no pharmacological studies to support these clinical impressions. In re-examining data, presented by Gertner, Paasonen and Giarman³, demonstrating the presence of 5-hydroxytryptamine when the superior cervical ganglion was perfused with iproniazid, it was seen in these experiments that iproniazid blocked ganglionic transmission. Furthermore, a definite dosage–response relationship was found; minimal blocking effects were seen with 100 µgm. of iproniazid per ml. of perfusion fluid and complete blockade when 400 µgm./ml. was used. The appearance of 5-hydroxytryptamine in the perfusate occurred a considerable time after the appearance of ganglionic blockade. In ascertaining the effects of the p-tolyl ether of choline, the authors found that it, too, would block transmission, but no 5-hydroxytryptamine appeared in the perfusate.