Fig. 1. Isoflurane reduces the carbachol-evoked [Ca²⁺]^cyttransient in the presence, but not in the absence, of extracellular Ca²⁺. The application of isoflurane was started 10 min before the 2 min carbachol stimulation. (  A–D ) Cells exposed to 1 mm carbachol (CAB) in the absence or presence of 1 mm isoflurane and in the presence of physiologic concentration of extracellular Ca²⁺(1.5 mm). The averaged carbachol-evoked [Ca²⁺]^cyttransient (  A ) and the corresponding measurements: peaks (  B ), areas (  C ), and widths at 50% peak height (  D ) of the carbachol-evoked [Ca²⁺]^cyttransient in the absence and presence of isoflurane. (  E–H ) Cells exposed to 1 mm carbachol in the absence or presence of 1 mm isoflurane after reducing the concentration of extracellular Ca²⁺to 150 μm. The averaged carbachol-evoked [Ca²⁺]^cyttransient (  E ), and the corresponding measurements: peaks (  F ), areas (  G ), and widths at 50% peak height (  H ) of the carbachol-evoked [Ca²⁺]^cyttransient in the absence and presence of isoflurane. Units: Peaks (Δ ratio 340/380), Areas (ratio 340/380* ms), and Width at 50% peak (ms). The horizontal bars in A and E indicate a 2-min period. The results were expressed as mean ± SEM, except for panels A and E, where they were expressed only as means. Asterisks indicate a statistically significant difference  (*P < 0.001, unpaired two-tailed Student  t tests) between control and isoflurane. The baseline values (absolute ratio values before the addition of carbachol) were not statistically different (  P > 0.05) between control and isoflurane in the presence of either high (1.5 mm) or low (150 μm) extracellular Ca²⁺(data not shown). The data for parts A–C are taken from an earlier study and are shown here for comparison purposes. The (n) indicate the number of experiments for each condition .