Studies on the hypotensive action of dihydroergokryptine (DHK) and epinephrine-reversal in the dog and cat.

Recently, two important steps in pharmacology on the partial synthetized derivatives of ergot alkaloids were made by a group of investigators in Switzerland. One was the hypotensive action of the hydrogenated alkaloids of the ergotoxine group and the other was the psychogenic or hallucinogenic action of lysergic acid diethylamide (LSD). The hydrogenated alkaloids of ergotoxine which is composed of three alkaloids (ergocristine, ergocornine and ergokryptine), differ from the natural alkaloids in being much less toxic and in having a hypotensive activity. The hypotensive action was due to mainly central origin and partly peripheral adrenolytic action, but they have a slight vasoconstrictor action upon the peripheral blood vessels (Hoobler and Dontas, 1953 (1)). Konzett and Rothlin (1953) (2) reported some analytical results on the site of action of the hydrogenated ergot alkaloids and the pathways conducting vasodilator impulses from the brain centers. Previously, Rothlin (1949) (3) demonstrated that the hypotensive action of these alkaloids is markedly influenced by peripheral vascular tone in his spinal cat experiments. This report is concerned with: 1) the quantitative investigation of the blood pressure response and bradycardic and adrenolytic effects of DHK in the dog under two kinds of anesthesia, 2) the mode of action of the hypotensive action of DHK and the epinephrinereversal induced by DHK in the intact and spinal cat, with special references to the relation between the vasotone and the two responses.