Biosynthesis of ubiquinone and ubichromenol in vitamin A-deficient rats

Abstract

1. 1. The concentrations of ubiquinone and ubichromenol increased in the livers, but not in the intestines and kidneys, of rats maintained on a diet deficient in vitamin A. 2. 2. After short time intervals ( e.g. 2 h) following administration of the tracer, incorporation of [2- 14C]mevalonate into ubiquinone and ubichromenol in livers of vitamin A-deficient rats was lower than for normal animals; this was in contrast to later times ( e.g. 72 h) when it was higher. 3. 3. The “newly synthesized” ubiquinone in livers of vitamin A-deficient rats was distributed in all the cell fractions without specific localization. 4. 4. Absorbed exogenous [ 14C]ubiquinone and [ 14C]ubichromenol were retained in the livers of vitamin A-deficient rats to a larger extent and for a longer time than in the normal animals. 5. 5. The results suggest that the accumulation of ubiquinone and ubichromenol in the livers of vitamin A-deficient rats is due to lowered catabolism and not to increased rate of synthesis.