Interaction of penicillin and pentobarbital with inhibitory synaptic mechanisms in neocortex.

摘要: 1. In this study we characterized the responses of neocortical neurons to iontophoretically appliedγ-aminobutyric acid (GABA) and examined how these GABA as well inhibitory postsynaptic potentials (IPSPs) were affected by presence penicillin or pentobarbital. Intracellular recordings obtained from slices rat neocortex maintainedin vitro; injection dye Lucifer yellow indicated that primarily pyramidal neurons. 2. Orthodromically evoked always depolarizing at cell's resting membrane potential. Such could easily be reversed in polarity cell 10–15 mV, suggesting response consisted partly an IPSP. In some cases, depolarization unmasked a small, short-latency excitatory potential (EPSP). Responses applied also rest. Biphasic hyperpolarizing-depolarizing occasionally observed upon neuron. 3. Bath application (1.7–3.4 mM) decreased amplitude IPSPs increased their time peak, effect associated with development epileptiform activity. Penicillin reduced maximum without affecting dose required obtain half-maximal response, noncompetitive antagonism. 4. Pentobarbital (100–200µM) prolonged course while producing leftward shift charge-response relation. These results suggest convulsant anticonvulsant pentobarbital have opposing actions on GABAergic inhibition neocortex.