Fig. 5. (A, B ) Effects of sevoflurane (3–5%) on increases in R^340/380(A ) and force (B ) caused by incremental increases in the extracellular Ca²⁺concentration ([Ca²⁺]e) during 40 mm K⁺depolarization in the fura-2–loaded, endothelium-denuded strips in the presence of guanethidine (3 μm). The protocol used in this experiment was identical to that shown in figure 1A, and the time control data were shown in figures 1C–E. After recording the control responses to 40 mm K⁺, the strips were treated with sevoflurane for 15 min before and during the subsequent cumulative application of various concentrations of Ca²⁺in the presence of the 40-mm K⁺depolarization. In these analyses, the maximal increase in either R^340/380or force induced by 40 mm K⁺before exposure to sevoflurane was assumed to be 100%, whereas basal values in normal PSS were assumed to be 0%. *P < 0.05 versus  control at each Ca²⁺concentration (n = 4). (C ) Effects of sevoflurane (3–5%) on the R^340/380–force relation in the fura-2–loaded strips; the R^340/380–force relation either in the absence or in the presence of sevoflurane was constructed from the data shown in A  and B . The data were best fitted with the second-order polynomial least-squares regression curves. #(A, C) The basal values in the Ca²⁺free solution, 2-mm EGTA solution before the application of various concentrations of Ca²⁺.