Effects of carbonyl compounds (4-hydroxyalkenals) originating from the peroxidation of liver microsomal lipids on various microsomal enzyme activities of the liver.

Carbonyl compounds released during the NADPH-Fe dependent peroxidation of liver microsomal lipids and identified as 4-hydroxyalkenals (almost entirely as 4-hydroxynonenal) while inhibiting microsomal enzymes (such as glucose 6-phosphatase and aminopyrine demethylase) which are affected by lipid peroxidation, have no effect on microsomal NADPH-cytochrome c reductase. The latter enzyme activity is unaffected (or even increased) when liver microsomes are allowed to peroxidize in the NADPH-Fe dependent system. NADPH-cytochrome c reductase, contrary to the other enzymes, is similarly unaffected after CCl4 poisoning, that is in a situation in which peroxidation of membrane lipids of liver endoplasmic reticulum has been unequivocally demonstrated. It appears therefore that the effects exherted by lipid peroxidation or by 4-hydroxyalkenals originating from lipid peroxidation parallel the effects of CCl4 intoxication in vivo.