Fig. 4. Pooled summary data for protocol part 1, postsynaptic receptor response to muscimol for halothane (top ) and sevoflurane (bottom ). The graphs present the inhibitory receptor response (ρ in %). ρ was calculated at D^maxand its 0.25, 0.5, and 0.75 fractions. At all dose rates, ρ was significantly greater at 1 minimum alveolar concentration (MAC) (filled bar) than at 0 MAC (open bar) for both anesthetics (**P < 0.01, ***P < 0.001). The receptor responses were linear in the studied dose range. The applied muscimol dose rate and the actual net decreases in Fⁿwere different for each individual neuron. Therefore, the relative change in ρ (Δρ) was used to compare the effects of halothane and sevoflurane on postsynaptic γ-aminobutyric acid type A receptor function (see Δρ, fig. 5).