NADP pool state and activity of NADP-dependent dehydrogenases in the heart tissue of adult and old rats during immobilization stress

To reveal the reasons of age-specific change of heart sensitivity to stress, the content of oxidized and reduced NADP and activity of NADP-dependent dehydrogenase in myocardium of adult and old immobilized rats have been studied. It has been established that in the process of aging the amount of reduced NADP decreases in the old rat heart. At the same time the activity of NADP-dependent dehydrogenase decreases in postmitochondrial fraction of old rat myocardium as compared to adult rats. There is no change in the amount of reduced NADP in the heart of both rat age groups after 30-minute immobilization. The activity of NADP-dependent dehydrogenase in postmitochondrial fraction of myocardium in adult rats remains on the initial level while activation of NADP-dependent malate dehydrogenase and glucose 6-phosphate dehydrogenase appears in old rats.     

Catalase activity in the myocardium during stress in adult and aged rats]

The study of catalase myocardium activity at stress in adult and old rats has been performed. It has been revealed that the formation of immobilization stress is accompanied by the enzyme activity stimulation. The expression of this effects is more significant in adult animals. Experimental data concerning the possible role of peroxidation lipids in myocardium catalase stress activation and its age modulation are given.     

Features of energy metabolism of myocardial mitochondria and their ultrastructure in normal and immobilized rats of different animal social rank

The oxidative and phosphorylating functions of mitochondria (M) and their ultrastructure were studied in the myocardium of normal and 6.5-hour immobilized rats that belonged to different zoosocial groups. M from dominant rats under normal conditions were shown to exhibit higher energy and to possess better respiratory energy regulation than those of "outcast" rats. However, the ultrastructure of M had no group specificity in normal. The immobilization caused more profound changes in M from the dominant rats and led to a more pronounced swelling of M in the myocardium of the above rats than in the "outcast". M from the subdominant rats were most resistant to an immobilization stress.     

Age-related peculiarities of change in content of free radical oxidation products in muscle during stress

The age-dependent peculiarities of stimulation of free radical processes in subcellular fractions of skeletal muscle of rats subjected to long-term immobilization stress were studied in order to improve knowledge about changes of muscular tissue during ontogenesis. It is found that adult animals do not show accumulation of proteins carbonyls, TBA-reactive substances, and Schiff bases in subcellular fractions of the thigh muscle when immobUized. Long-term immobilization causes apparent manifestation of oxidative stress only in mitochondrial fraction in pubertal rats. Mitochondrial oxidative stress defense systems are sufficiently effective, however, direction of pathways of free radical oxidation carbonyl products catabolism alters in the cytoplasm of myocytes in old rats under long-term immobilization conditions.     

Energy metabolism in muscle tissue during hypokinesia of various durations

The state of energy metabolism in skeletal muscles and myocardium of albino rats was studied under long hypokinesia. It is established that on the 30th-70th days of hypokinesia endogenic fatty acids, whose oxidation promotes the uncoupling of oxidative phosphorylation and inhibition of the creatine phosphokinase reaction, are the main substrate of energy metabolism. In blood there occurs hyperlipemia and a decrease in the glucose content. A further immobilization results in predominance of succinate-dependent respiration, in blood there occurs a certain decrease in lipemia, normalization of the glucose level and an increase in the urea content.     

Changes in the tetrapolar rheographic indices of adult and old rats under stress]

Experiments with adult (8-10 months) and old (24-26 months) male rats were carried out to investigate the effect of stress on the values of central hemodynamics and inotropic cardiac function--stroke volume, minute volume, stroke index, as well as output volume rate, output volume rate index and systolic frequency. It is found that stress causes more significant disturbance of inotropic function in old rats as compared with adult animals. This disorder occurs earlier in old rats. Probably it is a result of more pronounced damaging effect of the stress on the myocardium of old rats against the background of decreased compensatory systemic abilities.     

Normalization of the stress-induced cardiac rhythm disturbances by activation of the positive emotiogenic area of the lateral hypothalamus in the rabbit

Results of experiments indicated, that activation of the positive emotiogenic areas of the lateral hypothalamus abolished what may be considered emotionally induced cardiovascular disturbances. The by immobilization and hypothalamic defence area stimulation provoked increase of blood pressure and heart rate returned to control values, the giant T waves of ECG and dysrhythmias if present disappeared. The morphological abnormalities in the subcellular structures of the myocardium due to prolonged stress stimulation, could not be annulled by the evoked positive emotions. On the other hand the activation of the positive emotiogenic area of the hypothalamus preceded and overlapped with that of the defence area and immobilization, it prevented the functional as well as morphological cardiovascular changes.     

Effect of isoprenaline on 85Sr accumulation in the myocardium of the adult rat

The administration of a single dose of isoprenaline to adult male rats stimulated 85Sr uptake by their blood, liver and myocardium. Whereas the 85Sr concentration in the blood and liver rose by only 36% and 42% respectively, the increase in the various compartments of the heart was 5-7 times this value. This finding is also documented by the increase in the ratio of the 85Sr concentration in the heart and blood. The increase observed in 85Sr accumulation in the myocardium is comparable to the repeatedly described changes which occur in radioactive calcium after the administration of isoprenaline.     

RhNRG-1β Protects the Myocardium against Irradiation-Induced Damage via the ErbB2-ERK-SIRT1 Signaling Pathway

Radiation-induced heart disease (RIHD), which is a serious side effect of the radiotherapy applied for various tumors due to the inevitable irradiation of the heart, cannot be treated effectively using current clinical therapies. Here, we demonstrated that rhNRG-1β, an epidermal growth factor (EGF)-like protein, protects myocardium tissue against irradiation-induced damage and preserves cardiac function. rhNRG-1β effectively ameliorated irradiation-induced myocardial nuclear damage in both cultured adult rat-derived cardiomyocytes and rat myocardium tissue via NRG/ErbB2 signaling. By activating ErbB2, rhNRG-1β maintained mitochondrial integrity, ATP production, respiratory chain function and the Krebs cycle status in irradiated cardiomyocytes. Moreover, the protection of irradiated cardiomyocytes and myocardium tissue by rhNRG-1β was at least partly mediated by the activation of the ErbB2-ERK-SIRT1 signaling pathway. Long-term observations further showed that rhNRG-1β administered in the peri-irradiation period exerts continuous protective effects on cardiac pump function, the myocardial energy metabolism, cardiomyocyte volume and interstitial fibrosis in the rats receiving radiation via NRG/ErbB2 signaling. Our findings indicate that rhNRG-1β can protect the myocardium against irradiation-induced damage and preserve cardiac function via the ErbB2-ERK-SIRT1 signaling pathway.     

Existence of cardiac PNMT mRNA in adult rats: elevation by stress in a glucocorticoid-dependent manner

Phenylethanolamine N-methyltransferase (PNMT) is the enzyme that synthesizes epinephrine from norepinephrine. The aim of this study was to determine potential PNMT gene expression in the cardiac atria and ventricles of adult rats and to examine whether the gene expression of this enzyme is affected by immobilization stress. PNMT mRNA levels were detected in all four parts of the heart, with the highest level in the left atrium. Both Southern blot and sequencing verified the specificity of PNMT detected by RT-PCR. Single immobilization for 2 h increased gene expression of PNMT in both atria and ventricles. In atria, this effect was clearly modulated by glucocorticoids, because either adrenalectomy or hypophysectomy prevented the increase in PNMT mRNA levels in response to immobilization stimulus. This study establishes, for the first time, that PNMT gene expression occurs in cardiac atria and also, to a small extent, in ventricles of adult rats. Immobilization stress increases gene expression in atria and ventricles. This increase requires an intact hypothalamus-pituitary-adrenocortical axis, indicating the involvement of glucocorticoids.     

Respiratory chain defect of myocardial mitochondria in idiopathic dilated cardiomyopathy of Doberman pinscher dogs.

Idiopathic dilated cardiomyopathy (IDCM) is a primary myocardial disease of unknown cause. We tested the hypothesis that IDCM was associated with a myocardial metabolic defect by determining a comprehensive biochemical profile of metabolite concentrations and enzyme activities for the major metabolic pathways of the myocardium. We used the Doberman pinscher breed as a naturally occurring canine model of IDCM and compared its myocardial profile with that of healthy adult mongrels. Compared with controls, myocardium in IDCM had markedly reduced mitochondrial electron transport activity and myoglobin concentration, in association with acidosis and energy depletion following anoxic challenge: 60% decreased NADH dehydrogenase and 50% decreased ATP synthetase activities; 90% decreased myoglobin concentration; and 30% reduced ATP and 50% increased lactate and proton concentrations. Sarcoplasmic reticulum Ca(2+)-transport ATPase was decreased by 42%. There was a 15% compensatory increase in fatty acid oxidation and Krebs cycle activity. Other biochemical changes were mild by comparison with the mitochondrial defects. We conclude that IDCM is associated with a marked impairment of mitochondrial production of ATP, arising from decreased activity of the mitochondrial electron transport system, including myoglobin. These changes may be secondary to an underlying genetic defect or may indicate a deficiency of the mitochondrial respiratory chain that predisposes this breed to heart failure.     

Liver, Brain, and Heart Metallothionein Induction by Stress

To date, stress has been reported to induce metallothionein (MT) synthesis in the liver only. In the present experiment, the effects of food and water deprivation alone or of immobilization stress plus food and water deprivation on liver, brain, and heart MT have been studied in adult male rats. Liver and brain MT levels were increased by immobilization stress as soon as 6 h after the onset of stress. Eighteen hours of immobilization, which is accompanied by food and water deprivation, further increased liver and brain MT levels and significantly increased heart MT content. A specific effect of immobilization was evident in all three tissues, because the effect of food and water deprivation alone was significantly lower than that of immobilization plus starvation. Changes in MT apparently were not related to changes in cytosolic Zn.     

一次性力竭运动对大鼠PHB1表达及线粒体功能的影响

目的：观察一次性力竭运动后大鼠脑、心、骨骼肌组织和线粒体中PHB1含量的变化及对大鼠线粒体功能的影响,探寻PHB1与线粒体功能和能量代谢的关系。方法：健康雄性SD大鼠40只,随机分为2组（n=20）：对照组和一次性力竭运动组,大鼠进行一次性急性跑台运动建立力竭运动模型。收集各组大鼠的心、脑和骨骼肌组织样品并提取线粒体,检测其呼吸功能和ROS的变化。用Western blot方法检测组织和线粒体中PHB1蛋白表达水平;用分光光度计检测各器官中ATP含量以及线粒体中复合体V活性（ATP合酶活性）。结果：①一次性力竭运动后脑、心肌、骨骼肌中ATP含量显著性降低;②一次性力竭运动后脑、心肌、骨骼肌线粒体中复合体V活性、RCR、ROS显著性降低,ST4均显著性升高,ST3无显著性差异。③一次性力竭运动后心、脑、骨骼肌线粒体中PHB1的表达显著性减少。④通过相关性分析得出：一次性力竭运动后心、脑、骨骼肌中ATP含量与心、脑、骨骼肌中复合体V活性呈正相关;心、脑、骨骼肌中ATP含量和心、脑骨骼肌中PHB1的表达呈正相关。结论：一次性力竭运动后,降低线粒体氧化磷酸化功能,使大鼠脑、骨骼肌线粒体内ROS生成增加,PHB1的表达、ATP含量和复合体V活性均下降。一次性力竭运动使得大鼠线粒体内PHB1表达降低,线粒体功能减弱,机体能量代谢降低。     

Study of ECG, parameters of external respiration and motor activity of rats of different ages during acute poisoning with fluoroacetamide

Acute poisoning with fluoroacetamide (FAA), an efficient blocker of the tricarboxylic acid cycle, was studied in newborn and adult Wistar rats. FAA was administered once: to adult rats at a dose of 11 mg/kg peros, to the 7-day old rat pups at doses of 3 and 50 mg/kg subcutaneously. For 7 days after the poisoning, ECG, respiration, and motor activity were recorded. Based on the obtained data, clinical analysis of ECG and analysis of the heart rate variability (HRV) were performed to evaluate the state of the autonomic nervous system. Administration of FAA to adult rats leads to pronounced disturbances in activities of cardiovascular and respiratory systems. The most dangerous is development of acute pulmonary heart and of respiratory disorder. Characteristic is development of diffuse myocardial alterations. In newborn rat pups, statistically significant disturbances of cardiac activity and respiration are absent. The rat pup death occurs due to the total organism exhaustion accompanied by arrest of development. In adult rats, during intoxication, the appearance of bursts of combined cardiac and respiratory tachyarrhythmias can be observed, as well as of regular high-amplitude convulsive inhalations following in the decasecond rhythm. In rats of all age groups, injection of FAA, after a brief increase of role of humoral-metabolic and sympathetic activity, leads to the gradual steady predominance of parasympathetic effects on HRV. These data can serve as a confirmation of that under conditions of inhibition of the Kreps cycle enzymatic reactions there occurs activation of physiological processes resulted from activity of alternative metabolic pathways. This statement is also confirmed by the absence of the ontogenetically fixed inhibition of the spontaneous motor activity in the FAA-poisoned rat pups. This also confirms our earlier statement about importance of pentose phosphate cycle reactions for realization of the decasecond and minute rhythms and about the absence of rigid dependence of these rhythms on activity of neuronal structures.     

Immobilization stress in rat tissues: alterations in protein oxidation, lipid peroxidation and antioxidant defense system

We determined the effects of immobilization stress on antioxidant status, protein oxidation and lipid peroxidation in brain, liver, kidney, heart and stomach of rats. Sixteen male Wistar rats (3 months old) were divided into controls (C) and immobilization stress group (IS). IS rats were immobilized for 180 min/day for 15 days. Plasma corticosterone levels were increased in IS group. Copper,zinc-superoxide dismutase activities were increased in brain, liver and kidney, but decreased in the heart and stomach after immobilization. Catalase activities were increased in brain, kidney and heart, and decreased in liver and stomach. Selenium-dependent glutathione peroxidase activities were decreased in brain and kidney, but increased in heart and stomach. Reduced glutathione levels were decreased, while protein carbonyl, conjugated dienes and thiobarbituric acid-reactive substances levels were increased in all tissues. Our results showed that the response of antioxidant defense system to stress differs for each tissue, and protein oxidation and lipid peroxidation is induced by immobilization stress in peripheral tissues.     

Endotoxin challenge reduces aconitase activity in myocardial tissue

Sepsis impairs mitochondrial respiration but the mechanisms responsible are incompletely understood. We propose that Krebs cycle enzymes are inhibited in sepsis, contributing to reduced rates of oxidative phosphorylation. Hypothesis. The activities of Krebs cycle enzymes are decreased in endotoxemia and contribute to reduced rates of oxidative phosphorylation. Methods. Adult male rats received an intraperitoneal injection of either endotoxin or saline. Cardiac mitochondria were subsequently isolated and measures of mitochondrial respiration and enzyme activities performed. Main results. By 24 h post endotoxin administration, there was a 28% reduction in mitochondrial respiration (P = 0.0005) and a 24% reduction in aconitase activity (P = 0.001). Functional activity of the electron transport chain was unaffected. Conclusion. Our data demonstrate that in the heart, the administration of endotoxin significantly and selectively decreased aconitase activity in association with reduced rates of oxidative phosphorylation. We conclude that decreased activity of aconitase contributes to the endotoxin-stimulated reduction in mitochondrial respiration.     

Prevention of disorders of cardiomyocyte ultrastructure in experimental myocardial infarction in immobilization-induced stress by administration of thyroid hormones

In the experiment, carried out on 48 non-inbred male rats ultrastructural changes in cardiomyocytes in non-ischemized parts of the heart at experimental infarction of myocardium under conditions of immobilization stress have been studied, as well as possibility to correct these changes by means of thyroid hormones. The stress intensifies dystrophic processes, developed outside the infarction zone, increases the mass of the necrotized tissue, essentially decreases the areas occupied by mitochondria and myofibrils, as well as their ratio in the section area. Small doses of thyroid hormones prevent the heart from the damaging effect of the stressor: decreasing area; occupied by mitochondria, myofibrils and their relation in the section, as well as they stimulate intracellular regenerative processes (accumulation of polymorphous mitochondria with clearly manifested cristae, membranes of the endoplasmic reticulum) and decrease the myocardial necrotized zone). Thus, structural lesions, resulted from the effect of ischemic necrosis and stress, can be prevented by small doses of thyroid hormones+.     

Changes in the content of glycolysis products in the myocardium of adult and older rats under stress]

The experiments on adult (8-10 months) and old (24-26 months) male rats have been performed to determine the glucose content in myocardium as well as the content of pyruvic and lactic acid after the stress impact. Findings show that the maximum accumulation of glycolysis products and the reduction of glucose content occur 18-60 hours after the stress, the effect being more pronounced in old animals.