Drug antagonism studied on frog flexor reflex and on mouse motility.

This study concerns the effects of strychnine and caffeine on ethanol, pentobarbital and atropine-induced depression of mouse motility and of frog spinal reflex. Competitive antagonism was found for the interaction between caffeine and ethanol, caffeine and pentobarbital, strychnine and atropine and strychnine and pentobarbital. The same kind of interaction was found in the mouse motility and in the frog spinal reflex. An attempt is made to interpret the biochemical basis of the competitive antagonisms. The antagonism between strychnine and atropine may be explained taking into account the presynaptic action of atropine and the antagonism between strychnine and pentobarbital is in agreement with a GABAergic action of the barbiturates.