Figure 11. Inferences on [Ca2+] at release sites during buffer action and facilitation.
A, postulated reduction of [Ca2+]RS by external buffers. The ratio [Ca2+]n,b/[Ca2+]n,o, which is the inferred relative reduction in [Ca2+]RS in the presence of buffer, is calculated according to eqn (7). Individual values correspond to data points of Fig. 7 Squares and circles represent data from facilitating and depressing terminals contacting bitufted and multipolar cells, respectively. B, postulated increase in [Ca2+]RS during facilitation. Values (for terminals on bitufted cells only) are calculated according to eqn (9a). RF values are from Figs 8 and 9; [Ca2+]n,1 is the product of the corresponding value in A and the value of [Ca2+]n,o, which is 0.72 in facilitating terminals on bitufted cells. pmax was assumed to be 0.8.