Fig. 11.

Graphical determination of n as the quantal parameter modified by LT action. A, IPSC fluctuations during the course of LT82-induced blockage of ACh release were analyzed by nonstationary analysis using a window width for local linear fitting w = 33, and variance windowW = 21. A₁,I = f(t) plot. The set of I_mean is represented by asolid white line. A₂, The result of subtracting I values fromI_mean. A₃, The corresponding Var =f(I_mean) plot.B, C, The Var =f(I_mean) plots from experiments in which either LT82 (n = 11) or LT9048 (n = 5) was injected. Individual plots are indicated by different symbols and are scaled to theI_mean and Var values determined before LT injection. For clarity, only 1 point of 10 is plotted.A₃–C, The adjustment of the data by linear (solid straight line) or nonlinear regression analysis (dashed curves) is presented. Forr² values see Results. The linear Var =f(I_mean) relationships indicate that I_mean diminution is caused by a decrease in n, the number of active release sites.