Penicillin decreases chloride conductance in crustacean muscle: a model for the epileptic neuron.
The effects of penicillin were studied on the neuromuscular preparation of the ghost crab, Ocypoda cursor. Penicillin in doses lower than 2 mM reduced both the amplitude of inhibitory junction potentials and conductance increases induced by external application of GABA. The nature of the latter effect appears to be 2-fold, a weaker competitive inhibition and a more powerful non-competitive effech which may be ionophore blockade. Penicillin in concentrations above 2 mM diminished resting conductance, especially that of chloride. The action of penicillin is, in general, to decrease chloride conductance in this preparation. The crustacean neuromuscular preparation may provide a useful analogue for understanding penicillin evoked epilepsy. The reduced chloride conductance could explain decreased inhibition, increased excitation and depolarization shifts in cortical neurons.
D000818:Animals; D003386:Brachyura; D002462:Cell Membrane / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004827:Epilepsy / Q000139:chemically induced / Q000378:metabolism*; D018756:GABA Antagonists; D005971:Glutamates / Q000494:pharmacology; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects*; D009132:Muscles / Q000187:drug effects; D009431:Neural Conduction / Q000187:drug effects; D009469:Neuromuscular Junction / Q000187:drug effects*; D009474:Neurons / Q000378:metabolism; D010400:Penicillin G / Q000494:pharmacology*; D011950:Receptors, Cholinergic / Q000187:drug effects; D013570:Synaptic Membranes / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D002712:Chlorides; D018756:GABA Antagonists; D005971:Glutamates; D011950:Receptors, Cholinergic; D005680:gamma-Aminobutyric Acid; D010400:Penicillin G