Figure 4.

Results of Monte Carlo simulations indicating the number of vesicles released and the channel cooperativity as a function of number of open channels and the channel influx. A, Average number of vesicles released (maximum possible of 40) as a function of the number of open channels in the AZ for different magnitudes of single-channel Ca²⁺ current and different amounts of mobile buffer. B, Average number of vesicles released as a function of single-channel Ca²⁺ current for different numbers of open channels and different amounts of mobile buffer. C, Average channel cooperativity (maximum possible of 5) as a function of the number of open channels in the AZ for different values of Ca²⁺ current and different amounts of mobile buffer present. D, Average channel cooperativity as a function of Ca²⁺ channel current for different numbers of open channels and different amounts of mobile buffer present.