[Content of adenine nucleotides and creatinephosphate in brain, myocardium, liver and skeletal muscle under combined action of hypercapnia, hypoxia and cooling]. / Soderzhanie adenilovykh nukleotidov i kreatinfosfata v tkaniakh golovnogo mozta, miokarda, pecheni i skeletnykh myshts pri sovmestnom vozdeistvii giperkapniei gipoksiei i okhlazhdeniem.

Cooling of rats under conditions of hypercapina and hypoxia induced no changes in the content of adenine nucleotides in the brain and skeletal muscles and decreased their concentration in the liver and myocardium. The content of creatine phosphate increased in the brain, but had no changes in the other tissues. 48 hours after cooling the amount of adenine nucleotides in the brain was higher as compared with the initial values, that was due to an increase in the ATP concentration; in the other tissues the contents of adenine nucleotides did not differ from that of the intact rats. The repeated action (48 hours after the first influences) caused no changes in the contents of adenine nucleotides in skeletal muscles and decreased them in the myocardium and liver. In the brain their amount and the content of creatinephosphate were increased as related to the intact rats. In the brain and myocardium the level of NADPH decreased after the first action and 48 hours after impact it restored up to the inital values. After repeated impact the level of NADPH in the brain restored up to initial values, in the myocardium it was increased.

[Changes in lipid and carbohydrate metabolism in rat tissues under combined effect of hypercapnia, hypoxia and cooling]. / Izmeneniia Zhirovogo i uglevodnogo obmenov v tkaniakh krys pri sochetannom vozdeistvii giperkapniei, gipoksiei i okhlazhdeniem.

The cooling of rats under conditions of hypercapnia and hypoxia during the first 15 minutes increases the contents of free fatty acids, acetoacetate and beta-oxybutyrate in the tissues of the brain, myocardium, liver, skeletal muscles and blood and decreases them by the end of the effect (120 min later) down to the initial values, in the liver and skeletal muscles tissues the content of the mentioned intermediates falls lower the initial values. In the carbohydrate metabolism the amount of phosphoenolpyruvate 15 and 120 min after the action beginning and the amount of malate in the myocardium and brain at the end of the experiment increase to a different extent; the content of lactate rises only in the brain 30 and 120 min after the beginning of cooling. In the rat venous blood the value of pCO2 increases up to 71.8+/-6.0 mm Hg, the total content of CO2 rises, the values of the standard bicarbonates decrease and the pH value drops sharply down to 6.98+/-0.03. It is suggested that one of the main reasons of such changes in metabolism is development of hypercapnia state and acidosis and the resulted increase in intensity of the carboxylation processes in the tissues.

[Pyridine nucleotide content in the brain and myocardium of rats under combined effect of hypercapnia, hypoxia and cooling]. / Soderzhanie piridinnukleotidov v mozge i miokarde krys pri sochetannom vozdeistvii giperkapnii, gipoksii i okhlazhdeniia

In experiments with rats, subjected to single and repeated simultaneous effect of hypercapnia, hypoxia and cooling, contents of pyridine nucleotides (NAD, NADP, NAD-H2 and NADP-H2) and macroergic substances were studied and also the activity of dehydrogenases of the pentose pathway was determined in brain and myocardium. In brain NADP was not practically determined and in heart its content was increased after the first and the second treatments. Content of NADP-H2 was distinctly decreased in both tissues after the single treatment. NAD was not altered in the tissues in all the periods studied. The amount of NAD-H2 was decreased in brain after the single treatment and it was increased in myocardium after the repeated one. In the activity of dehydrogenases marked alterations were not observed. Total macroergic substances were not altered in brain after the single treatment and after the repeated one they were increased mainly due to the ATP increase. In myocardium total macroergic substances were decreased after the both treatments.

[Krebs cycle in tissue of rats subjected to combined effect of hypercapnia, hypoxia and cooling]. / Tsiki krebsa v takniakh krys, podvergnutykh sochetannomy vozdeistviiu giperkapnii, gipoksii i okhlazhdeniia

The content of the Krebs cycle substrates and activity of dehydrogenases corresponding to them were studied in the brain and myocardium tissues of the non-linear male rats adapted to acute hypoxia under conditions of the altered gas medium. The content of malate and succinic acid was studied in the liver and skeletal muscles only. In the brain the total activity of malate dehydrogenase (MDH, EC 1.1.1.37, 1.1.1.39) alpha-ketoglutarate dehydrogenase (KDH, EC 1.2.4.2) pyruvate dehydrogenase (PDH, EC 1.2.4.1) and isocitrate dehydrogenase (ICDH, EC 1.1.1.41-42) is shown to be decreased and kept to be lowered in all the periods of the study. No essential shifts in the activity of these dehydrogenases were found in the myocardium. The activity of succinate dehydrogenase (SDH, EC 1.3.99.1) in both tissues lowers 48 h after the effect of the mentioned factors. Simultaneously the greatest changes in the level of the substrates were observed in the myocardium, in the brain they were less developed. In the liver the content of malate increases without pronounced changes in the amount of succinic acid and in the skeletal muscles the level of malate and succinic acid lowers.