The in vitro effect of DDT and related compounds on the succinoxidase system of rat heart

Abstract

DDT and several of its related compounds were found to be inhibitory to rat heart succinoxidase at concentrations of from 10 −4 to 10 −5 M, the degree of inhibition being about 70–90% at the higher concentrations. This inhibition could also be shown for cytochrome oxidase, but not for succinic dehydrogenase. The inhibition was demonstrable when the insecticide or its derivatives were added to the enzyme system as alcoholic solutions. Cholesterol at the same concentrations did not inhibit succinoxidase. When DDT was present in an oil emulsion, only a slight inhibition could be shown toward the succinoxidase system, even though the concentration in the emulsion was 10 times that of the highest level in alcohol. DDA, the acetic acid derivative of DDT, and a known metabolite thereof, was much less inhibitory toward the succinoxidase and cytochrome oxidase systems, even at 5 × 10 −4 M.