Figure 5.

The sevoflurane (SF)-dependent Ca²⁺ affinity for the individual lobes assessed by isothermal titration calorimetry (ITC). ITC experiments were utilized to measure the affinity of CaM lobes for Ca²⁺ in the presence and absence of SF. (A) Upper panel: Typical ITC curve for CaM–Ca²⁺ interaction. Lower panel: Overlay of integrated ITC data for the N-lobe. Titrations consisted of 40 injections of 1 μL CaCl₂ at 1.6 mmol/L into the cell containing the N-lobe at a 20-fold lower concentration (0.5 mmol/L), and with SF concentrations at 0 (gray), 0.4 (green), or 20 mmol/L SF (red) The measurement performed with 0.4 mmol/L SF is pharmacologically relevant as it corresponds to the clinical blood concentration of SF at anesthesia (Franks and Lieb 1994; Streiff et al. 2004). (B) Bar graphs indicating the average ΔG and K_d for the N-lobe binding sites. The error bars indicate standard errors based on three independent measurements for each titration. Two-tailed paired t-test: *P = 0.047; **P = 0.0075.