[Spinal mechanisms of motor disinhibition following barbamyl administration]

Prior to and following an intravenous introduction of 250 mg of barbamil by the stimulation of the EMG method the authors studied the H-reflex and M-response of the soleus and gastronemius muscles. The use of singular electric stimula of an increasing intensity as well as multiple repetitions of singular stimula of equal intensity of depicted the following. Barbamil decreases the threshold and increases the amplitude of H-reflexes, and does not influence the M-response. When using pair stimula, barbamil shortens the period of absolute nonexcitation and the second phase of depression in the cycle of restituted H-reflexes to the second stimula in the pair. On this basis the author comes to the conclusion that the action of this preparation on the segmental apparatus of the spinal cord is expressed in an inhibition of gamma-impulsation, a blocking of inhibitive interneurons and an easier reflex excitation of alpha-motoneurons. The report deals with a discussion of these mechanisms for the effect of a prolonged disinhibition.