Action of Chloretone on Reduced Cozymaze Oxidation by Cytochrome c

Abstract

IT has long been known that anæsthetics, including barbiturates and chloretone, suppress brain respiration in vitro^1–3, the suppression occurring at concentrations causing narcosis when brain respiration is stimulated by increasing the potassium ion concentration of the medium in which the brain tissue is incubated⁴. Michaelis and Quastel⁵ concluded that anæsthetics, as represented by chloretone, suppress in the respiratory chain the activity of a flavoprotein forming a link between reduced cozymase (DPNH) and cytochrome oxidase. It was later shown⁶, in accordance with this conclusion, that ‘Amytal’ suppresses the oxidation, by brain mitochondria, of DPNH and its oxidative phosphorylations. In view of the increasing use of ‘Amytal’ as a tool in the investigation of respiratory systems, we have carried out experiments to observe whether chloretone is effective in the suppression of DPNH oxidation by cytochrome c in a tissue homogenate or mitochondrial system. Chloretone offers a definite advantage over sodium amytal in not being ionized in solution and hence in not interfering with electrolyte equilibria.