Figure 1. The experimental setup to record nerve-evoked excitatory junctional currents. A recording chamber (1 ml) containing the preparation was mounted on the stage of an upright microscope (Diaphot; Nikon, Tokyo, Japan) and the specimen was viewed with a x40 objective lens. A stimulating microelectrode and recording patch electrode were placed with visual control. Abdominal longitudinal muscles 6 or 7 of the first instar larvae were voltage clamped at -60 mV using the patch-clamp technique in the whole cell configuration.