Presynaptic alteration of [3H]GABA transport in hippocampus by amygdala kindling

gamma-Amino[2,3-3H]butyric acid ([3H]GABA) transport was investigated in hippocampal synaptosomes prepared from amygdala kindled rats. Kindling enhanced [3H]GABA uptake by 10-20%, while the Km of uptake and the kinetics of the release were unchanged. The dose response curve of the inhibition of [3H]GABA uptake by veratridine was altered by kindling: the K0.5 of inhibition and the Hill number increased and the curve became biphasic after a long period of stimulations. This effect was interpreted in terms of a modification of the functioning of the presynaptic fast Na+ channels which initially become more resistant to depolarization. In the long term, it appears that new Na+ channels develop that are more sensitive to the action of veratridine.