Neuromuscular glutamatergic and GABAergic channels

Our laboratory has worked extensively on glutamatergic and GABA-ergic channels, predominantly in crayfish, but also in locust, Drosophila and recently Ascaris. Channel currents were recorded in the different modes of the patch-clamp technique (Hamill et al., 1981). The opening kinetics of the channels were derived from open and closed time histograms obtained from single channel recordings. From these, channel conductances could also be evaluated. The most relevant data were obtained by very rapidly rising and falling pulses (time of change about 0.1 ms) of agonists applied to outside-out patches containing the respective channels (Franke et al., 1987). From such recordings we constructed dose-response curves for peak and steady-state currents, for the rise times of the currents and for the time constants of desensitization. In double-pulse experiments we measured recovery from desensitization and predesensitization due to low agonist concentrations. For most of the channel types, we succeeded in constructing a reaction scheme which in computer simulations mimicked channel behaviour to a good approximation.