Figure 5. The change in glutamate release versus the change in intrasynaptosomal [Calcium2+] ([Ca2+]i) transient observed in the presence of 1 or 2 MAC anesthetics or with decreased external [Calcium2+] (600, 400, 200, and 100 micro Meter, as indicated), where values are expressed as a fraction of the 1.3 mM Calcium2+ control values. The lines indicate the response anticipated if glutamate release is strictly a linear function of [Calcium2+] (n = 1) or if it is a function of a higher power of [Ca2+]i(n = 2 or n = 3)--that is, if two or three Calcium2+ are required to bind to a site responsible for activation of glutamate release, according to Equation 3