Activation and inhibition of 3H-strychnine binding to the glycine receptor by Eccles' anions: modulatory effects of cations.

The ammonium salts of Eccles' anions are inhibitors of 3H-strychnine binding. By contrast, the binding is activated by the sodium salts of these anions. This activation is due to an increase in the affinity for 3H-strychnine. Pretreatment of the membranes with acetic anhydride abolishes the effect of sodium salt, whereas ammonium salts remain unaffected. In the presence of chloride the inhibitory effect of ammonium predominates over the effect of sodium. These results suggest that the effect of Eccles' anions is profoundly modified by their counter-ions and that Na+ and ammonium are acting through distinct sites on the glycine receptor.