Figure 4. Cell functions controlled by mitochondrial complex I. Complex I function affects mainly two cytologic functions. (1) Generating a proton motive force across the inner mitochondrial membrane important for adenosine triphosphate synthesis and transport of metabolites across this membrane. (2) Prevention of membrane damage by maintaining a pool of the antioxidant ubiquinol. Either of these physiologic functions could be expected to have an effect on anesthetic sensitivity (see text).