[Vitamin A and NADP-dependent isocitrate dehydrogenase: difference in activity of mitochondrial and cytoplasmic isoenzyme fractions].

The effects of vitamin A excess on the activity of isoenzyme fractions of NADP-dependent isocitrate dehydrogenase from rat liver separated by polyacrylamide gel disc-electrophoresis was studied. Vitamin A was shown to activate mitochondrial isoenzyme of NADP-dependent isocitrate dehydrogenase and had but very slight effect on the cytoplasmic isoform. This effect was observed already after 24 hrs following the injection and was enhanced at increasing doses of the vitamin. The data obtained suggest that NADP-dependent isocitrate dehydrogenase is controlled by complex mechanisms. The possibility of independent regulation of activity of mitochondrial and cytoplasmic isoenzymes and a possible involvement of retinol in the regulation of activity of its mitochondrial isoform are postulated. It is assumed that vitamins, similar to hormones, can selectively influence individual isoenzymes.