Figure 1.

Extended blockade of neuromuscular activity increases synaptic strength because of the prolongation of the EPC. A, Superimposed EPCs from a control endplate (black) and an endplate in which synaptic activity was blocked by a TTX cuff for 8 d (gray). Although the peak amplitude of the EPC is similar, there is prolongation of EPC decay after block of activity. Each EPC is preceded by a stimulus artifact (arrow with long tail). B, Mean EPC amplitude in control endplates (black) and endplates in which activity was blocked for 7–10 d (gray). There is no statistically significant increase in EPC amplitude after block of synaptic activity (p = 0.55). C, Mean EPC integral in control endplates (black) and endplates in which activity was blocked for 7–10 d (gray). There is a statistically significant increase in total charge carried by the EPCs after blocking synaptic activity (p < 0.01). n = 9 control muscles and 6 muscles in which activity was blocked. Error bars represent the SEM.