Blockade of a late inhibitory postsynaptic potential in hippocampal CA3 neurons in vitro reveals a late depolarizing potential that is augmented by pentobarbital.
These experiments show that blockade of a late inhibitory postsynaptic potential (IPSP) in rat hippocampus by injection of GTP gamma s into a single monitored neuron, or by injection of pertussis toxin into the hippocampus, exposed a synaptic potential that was depolarizing relative to the early, GABAA mediated IPSP. The reversal potential of this late depolarizing potential (LDP) was 10-12 mV positive to that of the early IPSP. The response was augmented by 40-60 microM pentobarbital, and the augmented response appeared to be sensitive to picrotoxin, an antagonist of GABAA action. The LDP is comparable to a depolarizing GABAA synaptic response that had been previously observed only when synaptic behavior of slices was grossly altered by exposure to pentobarbital or 4-aminopyridine.
Thalmann
R H
RH
Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030.
D000818:Animals; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009433:Neural Inhibition / Q000187:drug effects*; D010424:Pentobarbital / Q000494:pharmacology*; D037342:Pertussis Toxin; D010852:Picrotoxin / Q000494:pharmacology; D051381:Rats; D013873:Thionucleotides / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D010424:Pentobarbital; D037342:Pertussis Toxin; D010852:Picrotoxin; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella