In vitro evidence for CCl4 metabolites covalently bound to lipoprotein micelles

AbstractCCl4-induced impairment of the lipoprotein secretion pathway of intact rat hepatocytes was carried out using 14CCl4 to check the possibility of binding to lipoproteins by CCl4 metabolites. After separation of different cell suspension fractions by means of ultracentrifugation and chemical precipitation procedures, a significant amount of the radioisotope was found covalently bound to the lipid and protein components of low density lipoproteins. Suitable experiments demonstrated that the bound radioisotope was represented by CCl4 metabolites and not by unactivated CCl4

Content and distribution of pyridine nucleotides in fatty livers

Oxidation of some substrates requiring DPN (glutamate, malate, pyruvate, ketoglutarate) is strongly decreased in fatty livers of rats, obtained either by injection of steatogenic poisons (CCl4, P) or by feeding with a diet deficient of choline. The decrease of oxidative power is particularly strong in mitochondria. Addition to these mitochondria of the supernatant fluid produces stimulation of the oxidative activity. Almost complete restoration of activity is produced both in homogenates and in mitochondria by addition of DPN. The concentration of pyridine nucleotides in fatty livers is strongly decreased. The extent of this decrease is particularly remarkable in mitochondria. A redistribution of pyridine nucleotides, with displacement of these substances from mitochondria into the supernatant fluid, occurs in fatty liver homogenates. The PN/PNH ratio is decreased in fatty livers. Synthesis of DPN in vitro through the Kornberg reaction and destruction of DPN are not modified. Both decrease of oxidation of glutamate and decrease and displacement of DPN occur in the livers of treated animals before the beginning of the accumulation of fat within the cells. The possible causes for the described phenomena and their importance for the pathogenesis of liver steatosis are discussed

Displacement of thiamine pyrophosphate from swollen mitochondria

The distribution of TPP in cytoplasm fractions of rat liver is studied. When the homogenate was prepared with 0.25M sucrose, about 300% of TPP was present in mitochondria. When the homogenization medium was distilled water, the amount of TPP present in this fraction was markedly decreased, while that present in the supernatant fluid was increased. Mitochondria suspended in 0.25M sucrose and incubated at 18° C for 10 min release in the suspension fluid about 20% of their TPP; under the same conditions, mitochondria suspended in water release about 65% of their TPP. An increased destruction of TPP was observed as a result of incubation of mitochondria in water at 18° C. The distribution of TPP in fatty liver homogenates prepared in 0.25M sucrose resembles strongly that observed for homogenates of normal rat liver prepared in distilled water; TPP was decreased in the mitochondrial fraction and correspondingly increased in the supernatant. Total TPP is decreased in fatty liver obtained by feeding rats on a diet deficient in choline. It remains practically unchanged in fatty liver produced by CCl4