[Primary afferent depolarization induced by gamma-aminobutyric acid injected into the central canal of the spinal cord in the cat].

The method of perfusion of the central canal of the cat spinal cord in vivo was used to study the effects of GABA on membrane potential changes in primary afferent terminals. It was shown with the use of the sucrose gap technique for recording the spinal dorsal root potentials that addition of GABA (5-50 mM/l) to the perfusate produced dose-dependent depolarization of the primary afferents. The depolarizing effect of GABA was abolished by bicuculline (2 mg/kg i. v.). The GABA-induced depolarization of the primary afferents was fully preserved after the synaptically induced depolarization of the primary afferents was reversed by addition of 20 mM/l Mg2 to the perfusate.