EFFECTS OF GUANIDINOACETIC ACID, γ-GUANIDINOBUTYRIC ACID AND γ-GUANIDINOBUTYRYLMETHYLESTER ON THE MAMMALIAN CEREBRAL CORTEX

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Abstract
The effects of gamma-guanidinoacetic acid (I), -butyric (II) acid and -butyryl-methylester (III) on the direct cortical response and the transcallosal response were investigated in the rabbit and cat. I suppressed the initial negative spike and augmented slightly the secondary negative wave of the direct cortical response in lower concentrations, abolished completely the initial negative spike in higher concentrations (0.5-1%) because of development of a surface positive wave. The effects of I on the transcallosal response consisted of 1) suppression of the surface negative wave, 2) augmentation and prolongation of the surface positive wave, 3) development of a late slow negative wave. Sometimes, there occurred repetitive positive shifts in potential following this late slow negativity. II augmented selectively the secondary negative wave, but did not affect directly the initial negative spike of the direct cortical response and augmented the surface negative component of the transcallosal response, leaving the surface-positive component unchanged. HI did not produce any change in the effects on evoked potentials. I, II and III corresponded neuropharmacologically to GABA, e -aminocaproic acid and aminocapronyl-methylester respectively.