THE EFFECT OF LOCAL ANESTHETICS ON THE RESPIRATION OF BRAIN HOMOGENATES

¹ Department of Pharmacology, Medical School, University of Virginia, Charlottesville Virginia

Cocaine, procaine, metycaine, butacaine, tetracaine and nupercaine inhibit the oxidation of glucose, succinate and ascorbate but do not inhibit the anaerobic glycolysis of glucose by brain homogenates. The oxidation and reduction of cytochrome c is inhibited; the anaerobic reduction of methylene blue in the presence of succinate and homogenate is not inhibited. These results indicate the blockage of the enzymatic chain is occurring at the cytochrome c-cytochrome oxidase level or at some factor necessary for the reduction of cytochrome c.

There is a wide range in the degree of inhibition by the anesthetics at 0.005 M and over a range of concentrations. Cocaine, procaine and metycaine give the least inhibition; tetracaine and butacaine are next in order; and nupercaine produces the greatest inhibition. There is a correlation between the in vitro and in vivo order of inhibition of these drugs.