Inhibition of cytochrome oxidase activity by local anaesthetics

Using a polarographic method, we studied the inhibition of mitochondrial electron transport at the cytochrome c oxidase site caused by eight local anaesthetics. The diversity of the types of inhibition observed indicate the importance of electrostatic interactions between the anaesthetic molecules and the membrane protein. A linear relationship was recognized between the anaesthetic activity of infiltration and the affinity for the enzyme. We also observed a significant relationship between this affinity and the octanol-water partition coefficient. This result suggests that lipophilic interactions are involved in cytochrome oxidase-anaesthetic binding. We tried to establish a parallel between this binding and the mechanism of anaesthesia involving the nerve membrane proteins.