[Effect of hypoxic stress on xenobiotic metabolism and activities of various isoforms of cytochrome P-450]

It was shown that animals divided into groups with respect to the initial sensitivity (low and high resistance) to hypoxia (lack of oxygen in air) differ by their liver monooxygenase enzyme complex reaction to the model acute hypoxia. Low-resistant rats exhibited an increase in cytochromes P-450 and b5, in the rate of oxidative metabolism of amidopyrine, aniline, and ethoxyresorufine, and in the rate of antipyrine elimination (manifested by a decrease in the elimination half time and by an increase in the elimination constant), which is evidence of the increasing activity of cytochromes P-450, 1A1, 1A2, 2C8, and 3A1. In response to acute hypoxia, highly hypoxia-resistant animals exhibited an increase in the rates of diazepam and methoxyresorufine metabolism, which reflected a higher catalytic activity of P-450, 2C6, 2B1, and 1A2 isoforms. At the same time, the rate of antipyrine elimination decreases (the elimination half-time increases, while the clearance and the elimination constant decrease).

Urine antipyrine metabolites in rats with different resistance to hypoxia subjected to cold stress

We studied antipyrine metabolism in rats with different resistance to hypoxia during adaptation to cold stress. Changes in the concentrations of some antipyrine metabolites at low temperature were associated with individual resistance to hypoxia. In low-resistant rats, antipyrine metabolism was suppressed from day 5 of cold exposure to day 3 of the recovery period. In highly resistant rats, antipyrine metabolism was inhibited on day 3 of cold exposure, but returned to normal on day 3 of the recovery period.

[The effect of reversible ischemia of the rat liver on antipyrine metabolism and the isoenzyme activity of cytochrome P-450]

The character of changes in the metabolism of antipyrine, etoxy-, methoxy- and pentoxyresurphin after total reversible ischemia of the liver was studied in rats. In animals highly resistant to hypoxia the metabolism of xenobiotics specific to cytochromes P-450 IA1, IA2, and IIB1 was inhibited; in subjects with low resistance to hypoxia only P-450 and IA1 activity was suppressed while the activity of P-450 IIB1 and IA2 increased 2-3-fold.

[Optimization of the diagnosis and treatment of anemias under exposure to aromatic-type organic solvents]

171 iron-deficient painters and 20 subjects with chronic intoxication with aromatic hydrocarbons were studied in a large aircraft construction factory. After correlative analysis of iron metabolism, ferritin, erythrocytes, diameter and perimeter of reticulocytes, length of service three types of iron-deficiency were identified: typical, with evident toxicity, with a high risk of toxic damage. An important role of lipid peroxidation activity and toxic erythrocyto-membranopathy for pathomorphosis of iron deficiency anemia and progress of toxic anemia is demonstrated. A differential approach to treatment of different anemia variants was used. The treatment included membranoprotectors (alpha-tocopherol, essential, lypostabil) and unspecific detoxication (SUMS-enterosorbent, unitiol).

[Fatty acid composition and functional status of erythrocyte membranes in patients with sepsis]

Distinct alterations in fatty acid composition and in the functional state of erythrocyte membranes were detected in 58 patients with sepsis; these alterations were phase-dependent and correlated highly with clinical picture. Considerable increase in content of saturated and monounsaturated fatty acids and a decrease in concentration of lipoproteins were found in erythrocyte membranes under inauspicious conditions of sepsis development. In these patients activities of superoxide dismutase and glucose-6-phosphate dehydrogenase were decreased, while content of SH-groups was lowered and lipid peroxidation was inhibited. The alterations observed in fatty acid composition of erythrocyte membranes and a decrease in metabolic activity of red blood cells may be responsible for hemolysis in patients with sepsis.

[The correction of the liver detoxifying function with phenobarbital and ziksorin before and after ischemia]

Rat experiments have shown preliminary administration of phenobarbital and zixoryn (before ischemia) fails to prevent the hepatic monoxygenase system from ischemic lesion, followed by profound destructive changes in the liver, though the functional activity of the microsomal system remained high. Phenobarbital and zixoryn induction of monooxygenases in the postischemic period contributed to the complete restoration of the levels of microsomal cytochromes and the metabolic activity of xenobiotics in the liver just in its early periods. It is concluded that it is advisable to use the inductors in the postischemic restorative period to correct the detoxifying function of the liver.

[The effect of acute hypoxia on antipyrine and isoniazid pharmacokinetics in rats with different resistances to oxygen deficiency]

Experiments in rats with different sensitivity to hypobaric hypoxia established bimodal distribution of antipyrine and isoniazide half-lives. Moreover, the low-sensitive rats were rapid acetylators and slow oxidizers, but the high-sensitive ones vice versa. The slowing down of antipyrine and isoniazide metabolism is supposed to be the most rational reaction of oxygen-dependent systems to the lack of oxygen in tissues.

[The effect of acute hypoxia on the fatty acid composition and lipid peroxidation of the liver microsomal membranes and blood plasma in rats with different resistances to oxygen deficiency]

The experiments in rats showed the changes in the fatty acids composition of lipids of hepatic microsomal membranes and lipids of blood plasma after acute hypobaric hypoxia to depend on individual resistance of animals to oxygen deficiency. In highly resistant rats the content of unsaturated fatty acids and lipid peroxidation activity in blood plasma increased. In low-resistant rats similar changes occurred in lipids of hepatic microsomal membranes.

[The characteristics of iron metabolism and the function of the transferrin-ceruloplasmin system in rats with different resistances to hypoxia]

Alterations of the same type in iron metabolism and the state of transferrin-ceruloplasmin system were demonstrated in rats with high and low sensitivity to hypoxia in acute hypobaric hypoxia. Immediately after acute hypoxia a decrease of all the parameters of ceruloplasmin and transport was demonstrated. A stimulating impact of acute hypoxia on ceruloplasmin and transferrin synthesis was observed which was most marked in low-sensitive rats on the third day after hypoxia.

[The metabolic activity of the erythrocytes and the characteristics of ferrokinetics in children with sepsis]

The examination of septic children has revealed characteristics of iron and red cell metabolism: deep and persistent hypotransferrinemia, normo- or hypersideremia, normal ferritin levels. Red cells of septic children contain low concentrations of ATPase, histidine, lipoproteins, there is compensatory enhancement of 2,3-DPG, G-6-PD SH-group activity. In terminal sepsis the activity of the above parameters drastically falls entailing hemolysis, anemia and severe hypoxia.

[Pharmacokinetics of antipyrine, nifedipine and diazepam in experimental myocardial infarct]

It has been shown, that antipyrine, nifedipine, diazepam pharmacokinetics changes in different ways after myocardial infarction. On day 7, 14, and 21 after myocardial ischemia antipyrine T1/2 increased considerably, and antipyrine Cl and Kel decreased. Nifedipine T1/2 increased on day 7 only. There were no diazepam pharmacokinetic changes during restoration period. However, microsomal diazepam metabolism changed significantly. Diazepam hydroxylation increased on day 7 of myocardial infarction, and on day 14 and 21 did not differ from the control. Diazepam metabolites content changed considerably during restoration period. Under myocardial infarction cytochrome P-450 isoenzymes, oxidizing present substances seem to be altered to different extent.

[Changes in fatty acid composition and lipid peroxidation activity in microsomal membranes of the liver in experimental myocardial infarct]

The experiments on rats have shown, that coronary artery ligation caused distinct alteration in fatty acids composition of microsomal lipids of the liver during restoration period. Within 7-21 days after artery ligation content of fatty acids saturated was increased, but concentration of arachidonic acid was decreased. In this period affinity of the fluorescent probe ANS to microsomal membranes and affinity of the cytochrome P-450 to aniline was significantly decreased. Stability of the cytochrome P-450 to impairment during lipid peroxidation induction in vitro within 7-14 days myocardial infarction was increased. However in 21 day stability of cytochrome P-450 was significantly decreased.

[The effect of alpha-tocopherol and lidocaine on the structural-functional rearrangement of liver endoplasmic reticulum membranes after induction with phenobarbital in the postischemic period]

Inhibition of an increase in total content of unsaturated fatty acids in microsomal lipids induced by phenobarbital, alterations of parameters of the fluorescent probe 1,8-ANS-binding with membranes as well as restrictions in induction of liver microsomal monooxygenase enzymatic system were detected during postischemic period after total liver tissue ischemia. Preadministration of alpha-tocopherol and lidocaine prevented distinctly the structure-functional alterations induced by phenobarbital in liver microsomal membranes during postischemic period. Possible factors responsible for limitations of the phenobarbital inducing effect during postischemic period are discussed.

[Functioning of the monooxygenase system of the liver in experimental myocardial infarct]

The experiments on rats have shown that coronary artery ligation reduces the content of microsomal cytochromes P-450 and b5 and causes amidopyrine-N-demethylation and aniline-p-hydroxylation disturbances that persist throughout a 3-week period of myocardial infarction. The investigation of spontaneous lipid peroxidation of microsomal membranes in myocardial infarction has shown that concentration of malonic dialdehyde in microsomal fraction significantly increased by the 7th day after coronary artery ligation, as compared to sham-operated rats.

[Structural changes in the lipid component of membranes of endoplasmatic reticulum in early and late periods after liver ischemia]

Total ischemia of rat liver tissue within 30 min caused distinct alterations in lipid component of endoplasmic reticulum membranes, which occurred within three weeks of the postischemic period. During this period the rate of microsomal lipids saturation was elevated due to an increase in the relative content of saturated fatty acids. Two-step alterations were observed in the patterns of fluorescent probe binding (I-amino naphthalene-8-sulfonate) as well as in sensitivity of cytochrome P-450 to the impairment in vitro after induction of lipid peroxidation in microsomal membranes. Within 1-3 days after the ischemia affinity of the fluorescent probe to microsomes was decreased, while stability of cytochrome P-450 to impairment during lipid peroxidation induction was increased. Within 7-14 days affinity of the fluorescent probe to membranes was markedly elevated and stability of cytochrome P-450 to the impairment in vitro was lowered in the reactions of lipid peroxidation.

[Prevention, using alpha-tocopherol and lidocaine, of damage to the monooxygenase system activity and ultrastructure of hepatocytes following acute ischemia of the liver]

The experiments on rats have shown that alpha-tocopherol and lidocaine pretreatment leads to a decrease in the level of ischemic cell necrosis in the liver. The volume of cell necrosis in the liver was significantly decreased (more than threefold) in the case of drug pretreatment. The combination of alpha-tocopherol with lidocaine fully prevented the decrease in N-dimethylation of amidopyrine and cytochrome P-450 and b5 concentration, and the development of destructive alterations of cytoplasmic reticulum in the unaffected rat hepatocytes. alpha-Tocopherol and lidocaine pretreatment was effective for the retention of the depression of microsomal monooxygenases by phenobarbital in remote periods after acute hepatic ischemia.

[Prevention of ischemic damage to the liver monooxygenase system with lidocaine and alpha-tocopherol]

In experiments on rats it was shown that the liver ischemia produces a decrease of the maximal rate of amidopyrine and aniline hydroxylation in microsomes on the 3rd day of the postischemic period. A considerable depth of aniline metabolism inhibition following hepatic ischemia is related to reduced affinity of cytochrome P-450 to substrates of type II. On the 3rd and 14th days of the postischemic period the Michaelis constant and the constant of spectral dissociation for aniline significantly exceeded the given kinetic parameters in control animals. Administration of alpha-tocopherol in combination with lidocaine prevented a decrease of the rate of amidopyrine N-demethylation, the concentrations of cytochromes P-450, b5 and prevented a reduction of cytochrome P-450 affinity to aniline.

[Prevention of damages to the microsomal monooxygenases in thermal ischemia of the liver by the separate and combined use of alpha-tocopherol, lidocaine and kontrikal]

It was found in experiments on the in vitro model of rat liver ischemia that ischemia initiates membrane lipid peroxidation and proteolysis leading to damage of monooxygenase enzyme systems of microsomes. Preventive administration of alpha-tocopherol, lidocaine, contrykal and their combinations revealed the optimal protective effect of the combined administration of alpha-tocopherol with lidocaine and alpha-tocopherol with contrykal as compared to their separate use on the functional activity of microsomal monooxygenases at thermal ischemia of the liver. A combined approach to prevention of impairment of the liver function at its ischemia was recommended.

[Mechanisms of the damage to the liver monooxygenase systems in thermal ischemia]

It was shown in experiments in vitro that thermal ischemia of liver tissue leads to disorders in the function of membrane-bound microsomal monooxygenases. Disorders in the structural organization of membranes were also expressed in the inhibition of reactions of ascorbate-depending and fermentative peroxide oxidation of lipids and labilization of lysosomal membranes. Faults in the rate of amidopyrine n-demethylation and aniline n-hydroxylation correlate with the intensification of spontaneous peroxidation of lipids and activation of proteolytic processes in ischemia. The obtained data permitted to ground the approach to pharmacological prophylaxis of ischemic damages of liver microsomal monooxygenases.

[Structural-functional aspects of the postischemic recovery of the hepatocyte endoplasmic network in rats]

The experiments on rats have shown that total hepatic ischemia reduces the content of microsomal cytochromes P-450 and b5 and causes amidopyrine and aniline disturbances over a 2-3-week post-ischemic period. The analysis of hepatocyte ultrastructure has revealed the interdependence of structural and functional changes in endoplasmic reticulum during recovery period. The damage of monooxygenase inducibility correlated with stable decline in the number of fixed ribosomes in post-ischemic period.

[Characteristics of the ischemic disorders of xenobiotic metabolism in the liver of rats in the early and late stages of recovery]

It has been demonstrated in rat experiments that total ischemia of the liver leads to disorders of the metabolism of xenobiotics and endogenous substrates. Upset hexenal metabolism manifests in the prolongation of the hexenal-induced sleep and hexenal concentration elevation in blood plasma for 18 days of the postischemic period. Following exposure to ischemia liver microsomes show a decrease in the rate of amidopyrine, aniline and hydrocortisone hydroxylation. Hydrocortisone metabolism returns to normal by day 14, that of amidopyrine by day 21 of the postischemic period. Aniline metabolism gets disturbed to a greater degree, remaining 33.4% lower by day 21. It has been shown that the inducibility of microsomal monooxygenases is substantially restricted by days 7 and 14 of the postischemic period.