[Lipoprotein absorption and intracellular distribution in the adrenals of rats under physical load]. / Pogloshchenie i vnutrikletochnoe raspredelenie lipoproteidov v nadpochechnikakh krys pri fizicheskoi nagruzke.

Intravenous injections of the blood plasma iodinated lipoproteins (LP) to rats led to the marker binding and penetration into the adrenal cells. The most intensive absorption was specific to LPs of high density (LPHD) and, to a lesser degree, to LPs of low and very low density (LPLD, LPVLD). Intensive exercises produced an enhanced LPHD accumulation and a reduced LPLD level in the adrenal tissues. During subcellular fractionation of the adrenals LPVLDs were uniformly distributed among cellular organelles, LPLDs were accumulated in lysosomes and cytosol, whereas a large LPHD amount was collected in the small cytoplasmic membranes. The exercises led to an increase in LPHD binding with the fraction of small cytoplasmic membranes. The role of different LP classes in steroidogenesis processes is discussed. The differences, found in the absorption extent and localization of LP labelled, allowed one to suggest that the pathways of intracellular metabolism of several LP classes in the rat adrenals are distinctive.

[Features of the regulation of key enzymes involved in glycolysis and the pentosephosphate shunt in tissues with different functional specializations]. / Osobennosti reguliatsii kliuchevykh fermentov glikoliza i pentozofosfatnogo puti v tkanikah s razlichnoi funktsional'noi spetsializatsiei.

Under conditions of acute and chronic stress carbohydrate metabolism was decreased in muscles and liver tissue, increased in adrenal glands and unaltered in brain. cAMP at concentration 10(-5)M decreased the rate of glycolysis in liver tissue and increased it slightly in adrenal glands. The inhibitory effect of cAMP was not decreased by 2',3'-AMP and was reversed completely by the protein inhibitor of proteinkinase. cAMP inhibited hexokinase (HK) isoenzymes 2 and 3 as well as glucose-6-phosphate dehydrogenase (G6PD) isoenzymes 1 and 2, activities of HK 1 and G6PD 3 and 4 were unaltered. The decrease in activities of HK and G6PD appears to be related to phosphorylation of proteinkinase; lack of the effect of cAMP in adrenal glands was apparently due to absence of corresponding cAMP-dependent proteinkinase in this tissue.

[Effect of cortisol, adrenaline and ACTH on the absorption and intracellular distribution of protein-labelled lipoproteins by rat liver and adrenal tissues]. / Vliianie kortizola, adrenalina i AKTG na pogloshchenie i vnutrikletochnoe raspredelenie mechennykh po belku lipoproteidov tkaniami pecheni i nadpochechnikov krys.

One hour incubation of slices prepared from rat liver or adrenal glands with 125I labeled lipoproteins of different classes resulted in label binding and its penetration into the tissue cells. The greatest amounts of labeling were found in fractions of mitochondria, lysosomes, microsomes and the final supernatant. In relation to the weight unit, slices from adrenal glands consumed several times as much label as did liver slices. Epinephrine increased the amount of the label bound to the low density lipoproteins by several times in the fractions of large cell membranes, and decreased the 125I level in mitochondria. Cortizole increased the incorporation of the protein labeled lipoproteins very low density into the liver mitochondria. ACTH did not influence the incorporation or cellular distribution of the label in adrenal glands.

[Effect of cAMP on hexokinase and glucose-6-phosphate dehydrogenase isoenzymes in different white rat tissues]. / Vliianie tsAMF na izozimnye formy giksokinazy i gliukozo-6-fosfatdegidrogenazy v razlichnykh tkaniakh belykh krys.

Preincubation of liver and skeletal muscle cytosol obtained from Wistar rats in the presence of cAMP, ATP and MgCl2 inhibited hexokinase. The decrease in the total enzymatic activity was a consequence of inhibition of types 2 and 3 hexokinase. The activity of type 1 hexokinase was unchanged. Under the similar conditions there was a lowering of the total activity of glucose-6-phosphate dehydrogenase which arose from inhibition of types 1 and 2 of the enzyme. The activity of other glucose-6-phosphate dehydrogenase isozymes remained unchanged. Preincubation of adrenal supernatant with cAMP, ATP and MgCl2 did not alter the activity of both enzymes. This is likely to be due to the absence of the respective cAMP-dependent proteinkinases and to the features of the isozyme spectrum. The results obtained indicate that hexokinase and glucose-6-phosphate dehydrogenase can be attributed to the group of enzymes that are regulated by the "phosphorylation-dephosphorylation" mechanism.