Noise analysis of acetylcholine induced current at neuromuscular junctions of the mouse diaphragm

Miniature end-plate currents (mepcs) and membrane noise elicited by acetylcholine (ACh) iontophoresis were investigated at neuromuscular junctions of the mouse diaphragm. All the experiments were performed at a holding potential of -70 mV at a temperature of 19 degrees C. The equilibrium potential of the ACh response was estimated to be near zero; the mepcs displayed a peak amplitude of 2.46 +/- 0.13 nA (mean +/- S.E.) and relaxed exponentially with a time constant to 1.63 +/- 0.11 msec. Single ACh-activated channels had a conductance of 26.5 +/- 1.5 pS and a mean life time of 1.69 +/0- 0.13 msec.