Fig. 3. Concentration-dependent attenuation of state 3 mitochondrial respiration by 0.13, 0.39, 1.3, and 3.9 mm sevoflurane as a percentage of vehicle control when substrates for complex I (10 mm pyruvate with 10 mm malate) or for complex II (10 mm succinate with 10 μm rotenone) were given. Regression analysis showed exponential relationships (lines ) between the sevoflurane concentration as independent variable (x ), and the percentage of state 3 respiration as a dependent variable (y ) for both substrate groups:y = 77.0 ± 2.7 − (10.8 ± 5.2 · log x ) for pyruvate with malate (R2 = 0.11; P < 0.05) and y = 86.2 ± 1.2 − (15.7 ± 2.0 · log x ) for succinate with rotenone (R2 = 0.67; P < 0.05). The arrow indicates the concentration used for experiments with potential antagonists. All values are mean ± SEM, n = 8 per experimental group. *P < 0.05 versus Con.