Quantal release parameters during fade of endplate potentials.

An analog of hemicholinium-3 caused the fade of endplate potentials during repetitive stimulation at low rates. The quantal parameters of release were estimated during steady-state conditions before and in the presence of the drug. The fade of EPP's was associated with a decrease in quantal content (m). The decrease in m was, in turn, associated with a decrease in the binomial parameter n and an increase in the binomial parameter p. The changes in n and p are discussed in relation to available stores of transmitter and the probability of transmitter release.