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PubMedDate not supplied

[Effect of aggregation inducers and inhibitors on the pentosephosphate pathway enzymes of glucose conversion in the thrombocytes].

Experiments with rabbit platelets in vitro revealed differences in the effect of the aggregation inducers (ADP and thrombin) and the aggregation inhibitor cyclic AMP on the activity of the enzymes of pentosephosphate pathway of glucose oxidation. ADP and thrombin decrease significantly the activity of glucoso-6-phosphate dehydrogenase (G-6-PDH) and riboso-5-phosphate-metabolizing enzymes (R-5-PME) in platelets during aggregation, whereas cyclic AMP produces no appreciable effect on the G-6-PDH activity, but increases significantly the R-5-PME activity. ADP decreases and cyclic AMP raises substantially the activity of R-5-PME. The differences were also revealed in the effects produced by cyclic AMP and cyclic GMP on the enzymes of pentosephosphate pathway of glucose oxidation. Unlike cyclic AMP, cyclic GMP decreased significantly the activity of G-6-PDH. The activity of R-5-PME and cyclic GMP transketolase was more pronounced than that of cyclic AMP. Like cyclic AMP, cyclic GMP differs from ADP and thrombin in the action produced on the enzymes of pentosephosphate pathway of glucose oxidation.

Adenosine Diphosphate↗
PubMed1979

Pentosephosphate shunt activity of rat pancreatic islets: its dependence on glucose concentration.

Although several attempts have been made to establish a relationship between glucose concentration and pentosephosphate shunt (PPS) activity of pancreatic islets in vitro, no such relationship has been found. Recently it has been shown that exogenous insulin, when added in vitro, inhibited islet PPS activity. Since it was possible that the failure to detect such a relationship was due to insulin released into the incubation medium, we reinvestigated the subject, introducing GPAIS (guinea pig antiinsulin serum) to bind insulin in the medium. When five islets were incubated with 16.7 mM glucose for 90 min, the absolute rate as well as the percentage of islet PPS activity were found to be significantly higher (P less than 0.05) in the presence of GPAIS than in its absence. In the presence of GPAIS, the absolute rate and the percentage of islet PPS activity increased in a dose-related manner (18, 43, and 124 pmol/five islets.90 min and 2.3%, 3.2%, 9.4%, respectively) when the glucose concentration was raised from 5.6 to 11.1 and 16.7 mM. Our data, therefore, indicate that the activity of islet PPS activity in vitro depends on the concentration of glucose, provided that insulin does not accumulate in the incubation medium. This suggests that PPS activity might play a role in glucose-induced insulin secretion. However, whether the PPS contributes to the secretory mechanism by producing a signal for insulin secretion or by forming cofactors required by the secretory mechanism remains to be established.

Animals↗
PubMedDate not supplied

[Effect of insulin of dehydrogenases of pentosephosphate pathway and content of free fatty acids in rat kidney].

After administration of insulin into rats activity of dehydrogenases of pentosephosphate pathway was not altered in cortex and medulla of kidney as distinct from the liver tissue. Concentration of free fatty acids was slightly lower in soluble fraction of kidney cortex than in blood plasma and higher than in preparation from kidney medulla. Alterations in content of free fatty acids were not observed in the preparations of kidney of rats with alloxan diabetes.

Animals↗
PubMedDate not supplied

[Circadian rhythm of the activity of limiting enzymes of the pentosephosphate pathway in rat liver].

Activities of glucose-6-phosphate dehydrogenase and transketolase from rat liver tissue exhibited circadian rhythms with the maximal rate at 22 and 6 o'clock and minimal--at 14 o'clock (per 1 mg of liver protein and per 1 g of the tissue). Decrease in total activity of glucose-6-phosphate dehydrogenase at the day time was due to distinctly lowered activity of the minor isoenzyme components. Differences in activity of the enzymes were more than 100% at the maximal and minimal periods. The data obtained earlier and in the experiment reported herein suggest that alterations in activity of pentosephosphate pathway enzymes, observed in the states of stress reactions, are presumed to be compensated if they are within the limits of extreme circadian variations; activity of the enzymes, exceeding the circadian variation values, indicates decompensation in the state of carbohydrate turnover.

Animals↗
PubMedDate not supplied

[Enzyme activity of citrate, glyoxylate and pentosephosphate cycles during synthesis of citric acids by Candida lipolytica].

The activity of key enzymes of the citrate and glyoxylate cycles was compared in yeast cells during intensive synthesis of citric acids and in its absence in the course of growth of Candida lipolytica on glucose ("glucose" yeast cells) and on hexadecane ("hexadecane" yeast cells). Citrate and isocitrate were found to be formed by the yeast in the tricarboxylic acid cycle. The ability of the yeast for "overproduction" of citrate and isocitrate during its growth on glucose and hexadecane depends on the high activity of the key enzyme of cycle, citrate synthase, as compared with the activity of other enzymes of the tricarboxylic acid cycle. Citrate predominated among excreted acids during growth on glucose in conditions of nitrogen deficiency while isocitrate prevailed during growth on hexadecane. The predominating synthesis of citrate in the first case seems to be related to a lower activity of aconitase in the "glucose" cells as compared with the "hexadecane" cells.

Aconitate Hydratase↗
PubMedDate not supplied

[Effect of antipheins on indices of the activity of the pentosephosphate pathway for carbohydrate transformation].

Experiments set up on rabbits showed that with their intravenous administration in a dose of 10 mg/kg antiphein, aethimizol, allilnorantipheins and propylnorantiphein catalize the activity of the pentosophosphate mode of the carbohydrates transformation. The character of the action and the intensity of the effect depend on the features distinguishing the chemical structure of the substances, of particular importance here being changed conformation of the molecule.

Animals↗
PubMedDate not supplied

[Activity of enzymes of pentosephosphate pathway in the erythrocytes, myocardium and intercostal muscle of patients with mitral valve stenosis].

Decrease in activities of glucose-6-phosphate dehydrogenase and transketolase was observed in erythrocytes of patients with mitral stenosis. Development of the disease was accompanied by a further decrease in the enzymatic activity. The activity of the enzymes was increased in myocardium of atrium sinistrum at the IV stadium as compared with the III stadium of the disease. The glucose-6-phosphate dehydrogenase activity was decreased and the transketolase activity was unaltered in intercostal muscle of the patients.

Erythrocytes↗
PubMedDate not supplied

[Enzymatic activity of the pentosephosphate pathway of carbohydrate conversion in the experimental therapy of dermatitis in rats].

An increase in the activity of 6-phosphogluconate dehydrogenase, transketolase, ribose-5-phosphatase and intensive conversion of glucose in pentosophosphate pathway in erythrocytes were observed in experimental rat contact dermatitis. Ultrasonic therapy was used (0.2 w/cm2 at impulse regimen of generator) for prevention and treatment of the dermatitis. Treatment of the dermatitis by ultraphonophoresis of sinalar was shown to be a suitable method, which caused the normalization of biochemical and structural processes in skin.

Animals↗
PubMedDate not supplied

[Effect of estradiol dipropionate and its combination with insulin on pentosephosphate dehydrogenase cycle activity in the liver and the uterus].

Experimental investigations have shown estradiol-dipropionate and insulin to induce an elevated activity of glucose-6-phosphate- and 6-phospho-gluconate-dehydrogenase in the uterus and the liver. Insulin potentiates the inducing action of estradiol on the pentosophosphate cycle dehydrogenases when both of them are used concurrently. For insulin to display its inducing effect a definite level of endogenous estradiol in the organism is necessary, for insulin fails to exert a specific influence on the study of dehydrogenases in sexually immature and ovariectomized animals.

Animals↗
PubMedDate not supplied

[Enzymes of glycolysis and pentosephosphate shunt during early embryogenesis of the loach and the effect of glucose, lactate and fumarate on fertilized oocytes].

The regularities for changes were established in activity of hexokinase, glucokinase, glucosephosphate-isomerase, phosphofructokinase and glucose-6-phosphate dehydrogenaseduring the early development of loach (Misgurnus fossilis). It was found that a 30-minute incubation of fertilized loach eggs in the lactate or fumarate solutions decreases the glucokinase activity in the embryos of 3, 6, 9, 12, 15, 18 and 24 hours of their development, while the inhibitory effect of glucose on the enzyme activity is pronounced only after 18 and 24 hours of the development. A significant increase in the hexokinase and glucose-6-phosphate dehydrogenase activities under the above-mentioned conditions is observed only under the effect of glucose 9 and 6 and 9 hours, respectively, after fertilization. The glucose phosphate isomerase and phosphofructokinase activites under the effect of used compounds undergo no changes during the primary stages of embryogenesis.

Animals↗
PubMedDate not supplied

[Effect of vitamins PP and B1 on pentosephosphate pathway enzymatic activity in the kidneys of adrenalectomized rats].

The activity of glucose-6-phosphate dehydrogenase (EC 1.1.1.44), transketolase (EC 1.1.1.44), transketolase (EC 1.1.1.49), 6-phosphogluconate dehydrogenase (EC 2.2.1.1.) and also the thiaminediphosphate (TDP) content were investigated on the 8th day after adrenalectomy. With compensated sodium dysbalance the removal of suprarenals is shown not to change the activity of dehydrogenases, but it does lower the transketolase activity and the TDP level. A seven-fold administration to adrenalectomized animals of nicotinic acid, thiamine or a simple injection of nicotinamide normalize the transketolase activity through raising the TDP level. The fact of the reduced transketolase activity in the kidneys in hypocorticotism being due to deficiency of the co-enzyme is also proved by the presence of the TDP-effect in vitro.

Adrenal Glands↗
PubMedDate not supplied

[Effect of ether anesthesia on pentosephosphate cycle dehydrogenase activity in different parts of the brain].

Investigations carried out on 19 dogs demonstrated that under ether anesthesia and with the anesthetic concentration in the arterial blood of 126.4 +/- 15.4 mg% the activity of the glucose-6-phosphate and 6-phosphogluconate dehydrogenases in the optic and auditory areas of the brain cortex as well as in the median thalamus experiences no significant changes.

Anesthesia↗
PubMedDate not supplied

[Effect of an estrogen-progestin contraceptive preparation on the enzymatic acitivity of the pentosephosphate carbohydrate metabolic pathway and nucleic acid metabolic indices].

The effect of a long-term (14 days) combined introduction of mestranol and noiethinodrel in contraceptive doses on the activity of pentosophosphate routes enzymes of the carbohydrates metabolism, that of acid and basic ribonucleases and on the level of summary nucleinic acids in the uterus and liver in sexually mature female-rats was studied. It was found that the concentration of summary nucleinic acids in the tissues increases under the effect of the drug, the oxidative reactions enzymes become more active, while the activity of non-oxidative reactions enzymes of the pentosophosphate route and of acid and basic endoribonucleases in inhibited.

Animals↗
PubMedDate not supplied

[Pentosephosphate shunt enzymatic activity in the liver in its disordered innervation].

Partial denervation of the liver evoked the dissection of subphrenic vagus nerves and nerves of the hepatogastric duodenal ligament tissue stimulates synthesis of pentoses in the liver due to the oxidative mechanism and inhibits the process of unoxidative formation of pentoses. Three-four weeks after the operation one may observe a 72% increase in the activity of glucose-6-phosphate dehydrogenase in the liver tissue and a 29 and 21% drop in the activity of transketolase and enzymes, respectively, participating in metabolism of ribose-5-phosphate. The content of soluble proteins in the liver with deneravation is unchanged. A correlation is observed between these changes and those in the content of nucleic acids, an opinion is confirmed on the autonomous character of the oxidative and unoxidative phases of the pentose cycle.

Animals↗