Binding of ¹⁴C-Carbon Tetrachloride to Microsomal Proteins in vitro and Formation of CHCl₃ by Reduced Liver Microsomes

Abstract

1. Addition of CCl₄ to suspensions of reduced liver microsomes produces a difference spectrum with max. absorption at 454 nm. This absorption develops within approx. 5 min (37°).

2. Dehalogenation of CCl₄ to CHCl₃ by NADPH reduced liver microsomes displays similar kinetics.

3. The irreversible binding of ¹⁴CCl₄ to microsomal proteins proceeds more slowly than CHCl₃ formation.

4. The first step in CCl₄ liver toxicity is the very rapid formation of fast reacting intermediates. This step might occur between the binding of CCl₄ to cytochrome P-450 and the release of CHCl₃. The primary intermediates bind to liver lipids and proteins and also initiate lipid peroxidation.