A: electron micrograph of rat neuromuscular junction treated with peroxidase-conjugated α-bungarotoxin to label postjunctional AChRs. (From Engel et al. Neurology 27: 307–325, 1977, with permission.) B: time course of endplate potential and current. Horizontal bar, 2 ms; vertical bar, 40 nA (EPC) or 1 mV (EPP). (From Barrett EF and Magleby KL. Biology of Cholinergic Function, edited by A. M. Goldberg and I. Hanin. New York: Raven, 1976, p. 29–100, with permission.)