[Nicotinamide coenzymes in the regulation of cellular metabolism in various types of diabetes]. / Nikotinamidnye kofermenty v reguliatsii kletochnogo metabolizma pri raznykh tipakh diabeta.

Hypoglycemic and hypolipidemic effects of nicotinamide in insulin-dependent and noninsulin-dependent types of diabetes have been investigated. Hypoglycemic effect of nicotinamide in alloxan- and streptozotocin-induced diabetes resulted in activation of NAD+ biosynthesis and corresponding alterations in the redox state of free nicotinamide coenzymes. Increase in the free NAD+/NADH ratio was accompanied by inhibition of key gluconeogenic enzymes and by a decrease in the rate of 2-14C-incorporation into glucose in liver tissue and by inhibition of sorbitol formation in lens tissue. Nicotinamide exhibited hypolipidemic effect in db/db mice with noninsulin-dependent diabetes. The agent inhibited the enzyme of primary steps of lipogenesis, altered the structure of intercellular CoA pool and lowered the rate of lipid biosynthesis in liver tissue, thus normalizing blood lipoprotein compositions.

[Citrate transport in submitochondrial particles of the rat liver]. / Transport tsitrata v submitokhondrial'nykh chastitsakh pecheni krys.

The submitochondrial particles (SMP, inverted inner membrane vesicles of mitochondria of the turned out vesicles in internal mitochondrial membranes) of the rat liver are characterized for their ability to incorporate [14C]citrate depending on the concentration of exogenic citrate, temperature and time of incubation. The rate of citrate incorporation into SMP does not depend on the addition of the oxidation substrate into the medium, however in the presence of malate and phosphate it is sharply activated. 1,2,3-benzene tricarboxylase (1,2,3-BTC) is an active inhibitor of the citrate transport into SMP. The citrate transport is determined by the protonation-deprotonation processes of the carrier protein on the outer and inner side of the membrane. A decrease in the pH of the medium favours protonation of the carrier protein on the outer side of the membrane and intensifies [14C]citrate incorporation into SMP, whereas the pH increase inhibits this process. The effect of pH changes is less pronounced in the presence of K+ ions. Valinomycin in the K+ medium activates incorporation of [14C]citrate increasing the carrier protein deprotonation rate on the inner side of the SMP membrane. Protonophore separators intensify conductivity for H+ ions and remove the stimulating influence of valinomycin on the rate of [14C]citrate incorporation into SMP.