Glutamate receptor channel kinetics: the effect of glutamate concentration.

Single channel recordings from the locust muscle D-glutamate receptor channel were obtained using glutamate concentrations ranging from 10(-6) to 10(-2) M. Channel kinetics were analyzed to aid in the development of a model for the gating mechanism. Analysis of channel dwell time histograms demonstrated that the channel possessed multiple open and closed states at concentrations of glutamate between 10(-5) and 10(-2) M. Correlations between successive dwell times showed that the gating mechanism was nonlinear (i.e., branched or cyclic) over the same glutamate concentration range. The glutamate concentration dependence of the channel open probability, and of the event frequency, was used to explore two possible allosteric gating mechanisms in more detail.