Anion permeability of the inhibitory post‐synaptic membrane of the crayfish neuromuscular junction

Abstract

SUMMARY1. The membrane conductance of the crayfish muscle fibre was calculated and the increase in the membrane conductance brought about by the application of y-aminobutyric acid (GABA) was investigated under various conditions. The permeability of the activated inhibitory postsynaptic membrane was estimated from the conductance change.2. When the concentration of Cl-was changed by substituting CO-with methylsulphate, a linear relation was obtained between the membrane conductance change produced by GABA and the concentration of C1-. Cations have no appreciable effect on the GABA induced conductance change (less than 0-4 %).3. The conductance change produced by GABA on the inhibitory postsynaptic membrane was measured in various solutions in which the Clwas replaced by various anions. The degree of permeability depended on the anion species in the following order:Br-> Cl-> SON-> I-> N03-> HCOO-> C103-> C104-> BrO3-4. At high pH the conductance change produced by GABA was decreased, while at low pH it increased.5. These results show that the activated inhibitory post-synaptic membrane of crayfish muscle fibres has the characteristics of an anion selective membrane, suggesting the fixed positive charges in the inhibitory membrane.

Characterization and ionic basis of GABA‐induced depolarizations recorded in vitro from cat primary afferent neurones.

“…These results with foreign anions including the smaller ones support the suggestion made by Crain (1956) and Brooks & Werman (1973), that foreign anions may have a direct pharmacological action when substituted for Cl-in the extracellular solution. Takeuchi & Takeuchi (1967) also observed in the crayfish neuromuscular junction that the conductance change produced by GABA was graded according to the anionic species used to substitute for Cl-. The mode of the depression, examined with CH3COO-, CH3SO4-or HOCH2CH2SO3-in the present experiment, appeared to be of a non-competitive type suggesting that these anions and probably also other foreign anions do not affect the GABA recognition site, but rather, an allosteric site, or those Cl channels influenced by activation of the receptor.…”

“…The apparently anomalous behaviour of these two ions was explained by these authors on the basis of their physical chemical properties. The cerebral cortical neurone can pass larger anions and is, in this respect, more like crustacean muscle fibres (Takeuchi & Takeuchi, 1967).…”

GABA and lioresal actions on the identified Onchidium neuron.

“…In the muscle fibers of crayfish where the desensitization of GABA-induced current is less pronounced, the Hill coefficients of 2 and 3 have been reported by TAKEUCHI and TAKEUCHI (1967) and FELTZ (1971), respectively. In the present study, GABA-induced Icl of the Onchidium neuron gave Hill coefficient, n=1, for the dose-response curve.…”

Biomarkers and Therapeutic Drug Monitoring in Psychiatry

“…When GABA binds to GABA A receptor, facilitates the passage of chlorine, negatively charged ion, inside the cell through chloride channels. This influx of chloride increases the negativity of the cell (ie, a resting potential more negative membrane) causing it a greater difficulty to reach the action potential resulting, finally, in a cell stabilization (Barnard et al 1998;Kravitz et al 1963;Krnjević & Schwartz 1967;Sieghart & Sperk 2002;Takeuchi & Onodera 1972;Takeuchi & Takeuchi 1967, 1969.…”