Membrane Noise produced by Acetylcholine

Abstract

ECTROPHYSIOLOGICAL studies of the motor end-plate have shown that there is intermittent release of multi-molecular (“quantal”) packets of acetylcholine (ACh) from the nerve terminals, resulting in the appearance of discrete miniature end-plate potentials (m.e.p.p.). The number of molecular reactions which summate to make up a single m.e.p.p. is not known; it must be very large, for–with minimal doses of applied ACh—the membrane response seems to be continuously graded, even at amplitudes which are one or two orders of magnitude below that of the m.e.p.p. (see, for example, ref. 1, page 10).