Quantal parameters of transmission at the frog neuromuscular junction

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Abstract
Summary Estimates of quantal release parameters at frog neuromuscular junctions showed that alterations in [Ca2+]0 affected m (number of quanta), p (probability of quantal release) and n (stores of quanta available for release). The effect of [Ca2+]0 depended upon the initial value for p. When p was low, raising [Ca2+]0 increased m and p, but not n. However, when p was large, raising [Ca2+]0 had no further effect on p but increased m and n. During prolonged repetitive nerve stimulation to cause a decrease in m, n was decreased and p was increased. This finding was attributed to a failure of transmitter mobilization to maintain the stores of transmitter available for release.