Cinchocaine and amethocaine inhibit activation and activity of superoxide production in human neutrophils.

Local anaesthetics, cinchocaine and amethocaine, inhibited superoxide production in human neutrophils stimulated by phorbol ester, with IC50 (concentration of a drug giving 50% activity of control) values of 0.2 and 0.6 mmol litre-1, respectively. These anaesthetics inhibited protein (de)phosphorylation and mobilization of membrane-associated calcium, both of which are probable signal transmission mechanisms for the induction of superoxide production. Local anaesthetics also inhibited NADPH oxidase, responsible for superoxide production, with IC50 = 0.3 and 0.9 mmol litre-1, respectively. The results indicate that cinchocaine and amethocaine inhibit superoxide production in human neutrophils by affecting not only the catalytic activity, but also the activation, of NADPH oxidase.