Figure 6. MβCD does not block transmitter release.
A focal recording was made at boutons to detect transmitter release triggered either by axon stimulation or by current pulses delivered by the focal electrode. A, records of focal EPSCs evoked by presynaptic axon stimulation (cuff stimulating electrode). Records were taken at 30-min intervals in regular saline (left and middle panels). After the second record, MβCD was applied and 30 min later the EPSC was blocked. The right-hand panel shows a superimposed record obtained before and after application of MβCD. B, EPSCs generated by focal stimulation 1 min before each of the records in A. EPSCs generated by focal depolarization did not change after 30 min in regular saline. Following a 30-min application of MβCD, the focally stimulated EPSC amplitude was slightly increased. Similar results were obtained in four additional experiments. The results show that MβCD blocks evoked transmitter release by blocking presynaptic APs and not by blocking transmitter release per se.