Effect of acute exposure to carbon bisulfide vapour upon some components of the hepatic-microsomal enzyme system in rats

Adult female rats were exposed for 8 h to graded carbon-disulfide (CS₂) concentrations between 20 and 400 ppm. It was found that the lipid content of the hepatic microsomal fraction rose significantly due to an increase in phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, phosphatidylserine, sphingomyeline, lysophosphatidylcholine, cholesterol, triglycerides, diglycerides, and free fatty acids. The alterations occurred quickly and were completely reversible after exposure. Since the microsomal cytochrome P-450 content, as well as the activity of the microsomal NADPH cytochrome c-reductase, remained within the normal range following identical CS₂ exposures, it is assumed that the alteration in the lipid pattern of the endoplasmic reticulum is a causal factor in inhibition of the microsomal-oxidative drug metabolism, induced by identical inhalatory CS₂ doses. It is suggested that the altered lipid pattern impairs the microsomal membranes, thus affecting electron transport and resulting in a dysfunction of the oxidation chain. A slight elevation of the microsomal total protein was observed in relation both to a rise of the microsomal RNA content and an enhanced incorporation of [2,4 -³H]-L-phenylalanine into the liver microsomes after identical CS₂ exposures. It is considered that this finding might represent an unspecific stimulatory reaction.