Exercise-induced apoptosis in rat kidney is mediated by both angiotensin II AT1 and AT2 receptors.

Excessive physical exercise may lead to disturbance of the entire homeostasis in the body, including damage not only in skeletal muscles but also in many distant organs. The mechanisms responsible for the exercise-induced changes could include oxidative stress or angiotensin II. We previously showed that acute exercise led to apoptosis in kidney but not as a result of oxidative stress. In this study, we examined the role of angiotensin II and its AT1 and AT2 receptors in mediation of exercise-induced apoptosis in kidney. We clearly demonstrated that acute physical exercise induced apoptosis in renal cells of distal convoluted tubuli and cortical and medullary collecting ducts. Moreover, the cells displayed an increased expression of both AT1 and AT2 angiotensin II receptors and of p53 protein. The results suggest that angiotensin II could upregulate p53 expression in renal distal convoluted tubular cells and in the cells collecting ducts via both AT1 and AT2 receptors, which might be the crucial apoptosis-mediating mechanism in kidneys after excessive exercise.

Physical efficiency of 10-16-year-old boys with hearing impairment.

PURPOSE: The aim of our investigation was to estimate on hand of the above the physical efficiency value of hearing impaired children and compare them with healthy counterparts. MATERIAL AND METHODS: The investigation covered a group of 63 boys, 27 with hearing impairment (HI) and 36 healthy (R), 10-16 years old. The investigated subjects were divided into 2 groups according to their age: 10-12 and 14-16-year-old boys. For determination of cardio-respiratory system efficiency PWC170 (Physical Working Capacity) test was performed. PWC170 and VO2max indices were calculated using proper mathematical equations. RESULTS: The comparison of PWC170 and VO2max indices shows no statistically significant differences between investigated groups. Boys from younger HI group obtained higher PWC170 and VO2max values than boys from R group. In older groups, values of investigated indices were inversed in relation to younger groups. Boys from R group obtained higher values of investigated indices. CONCLUSIONS: Results received shows some trend, which is probably connected with isolation and absence of cohesion between auditory organ rehabilitation and physical efficiency development. There is necessity of integration programs construction, which will influence on comprehensive and proper growth of hearing impaired children.

Changes of lysosomal enzymes activity in the skeletal muscle fibers exposed to endurance exercise.

PURPOSE: To evaluate the effect of endurance exercise on the activity changes of selected lysosomal enzymes in particular types of rat muscle fibers, occurring by 0-4 days following the trial. MATERIAL AND METHODS: The experiment was performed on 3 month old male Wistar rats with body mass 250 +/- 25 g, exposed to single physical exercise on moving track (speed 17 m x min(-1), decline 0 degree, duration 87.5 +/- 27.5 min). Biochemical analyses were performed on homogenized fast-twitch FTa and FTb (m. gastrocnemius) and slow-twitch ST (m. soleus) muscle fibers of animals sacrificed 2 h (group II), 6 h (III) or 96 h (IV) after exercise and control group. The measurements considered protein concentration and the activities of beta-glucuronidase (beta-GRS), N-acetyl-beta-D-glucosaminidase (NAG), and arylsulphatase A (ASA). RESULTS: In FTa fibers, ASA and beta-GRS activities were elevated in all the exercised groups, with the most evident changes in animals tested 96 h post trial (group IV), while the peak of NAG activity was demonstrated 2 h after exercise (group II). In contrast, in FTb and ST fibers the levels of all the enzymes studied peaked 96 h after exercise, following the transient decrease in activity. CONCLUSIONS: The present study demonstrated that maximal running exercise, without the eccentric components, affects the activities of lysosomal enzymes in all types of rat muscular fibers. The lack of uniform activity profile for the lysosomal enzymes studied probably reflects the variety of their cellular functions.

The role of AT1 and AT2 angiotensin receptors in the mechanism of apoptosis in renal tubular cells after physical exercise.

Intensive physical exercise disturbs the entire homeostasis in the body and leads to changes in haemodynamic and metabolic alterations not only in skeletal muscles but also in many distant organs. In response to acute physical exercise, a decrease of the glomerular filtration may occur, followed by stimulation of the renin-angiotensin system (RAS). Recent studies have shown that both AT1 and AT2 angiotensin receptors may play a role in mediating the apoptotic process in the kidney. Our previous studies have demonstrated an occurrence of apoptosis in rat renal tubular cells after an excessive exercise. The aim of the present study was to determine the possible mechanism of exercise-induced apoptosis in rat kidney. The analysis was performed on kidneys of rats, subjected to treadmill running until exhaustion. Apoptosis was detected in paraffin sections by the TUNEL technique. The expression of AT1 and AT2 receptors in renal tubular cells was examined by immunohistochemistry and Western blot. Our results confirmed that apoptosis after physical exercise is present in renal distal tubular cells. Moreover, there was an increased expression of AT1 and AT2 receptors in distal tubular cells. These studies suggest that physical exercise may induce apoptosis by a mechanism, involving the activation of angiotensin AT1 and AT2 receptors.

Role of exogenous melatonin in reducing the cardiotoxic effect of daunorubicin and doxorubicin in the rat.

The aim of the studies was to examine the cardioprotective effect of melatonin during the anthracycline administration (daunorubicin, doxorubicin) in rats. Application of these drugs in chemotherapy is limited because of their cardiotoxicity. Rats of Buffalo strain were divided into groups according to the cytostatic drug used, its dose and sequence of administration (single intravenous [i.v.] dose of 10 mg/kg b.w., i.e., acute intoxication; 3 mg/kg b.w. weekly for 3 weeks, subchronic intoxication). Melatonin was administered subcutaneously before and after every injection of a cytostatic drug at a dose of 10 mg/kg b.w. The degree of cardiac muscle cell alterations was examined either histologically (Mean Total Score technique and the Billingham scale), or biochemically (levels of lipid peroxidation markers, malonyldialdehyde, and 4-hydroxyalkenals). Statistically significant decrease in cardiac muscle cell damage was noted with an aid of the Billingham scale after melatonin administration in acutely intoxicated doxorubicin-treated rats (p < 0.001). The similar phenomenon was observed using the Mean Total Score technique in case of acute daunorubicin or doxorubicin (p < 0.01 and p < 0.001, respectively) intoxications. A significant reduction in cardiac muscle cell lesions was detected either by the Billingham scale or by the Mean Total Score technique during subchronic intoxication with either of the anthracyclines when melatonin was given. Biochemical assays revealed significant decreases in malonyldialdehyde and 4-hydroxyalkenals levels following application of melatonin during either acute doxorubicin (p < 0.05) or subchronic daunorubicin (p < 0.01) intoxication. In summary, melatonin was found to exert a protective effect on the cardiac muscle cells, which was particularly evident after acute doxorubicin or subchronic daunorubicin intoxication, using either histological or biochemical methods.

Effect of cadmium intoxication on glucose utilization in energy metabolism of muscles.

The influence of cadmium intoxication on carbohydrate metabolism in skeletal muscles and liver of the male Wistar rats has been studied. Cadmium was administered as cadmium acetate in a dose of 0.3 mg Cd2+/kg body weight for three months. At the same time the control rats were injected with 0.9% NaCl. The animals were decapitated and samples of their skeletal muscles: the soleus muscle (composed mainly of red slow twitch fibers; ST) the gastrocnemius muscle containing two types of fibers (white fast twitch fibers FTb and red fast twitch fibers, FTa) and the liver were dissected out. In the samples of muscles, liver and serum contents of glycogen, glucose, pyruvate and lactate, as well as activities of hexokinase, pyruvate kinase and lactate dehydrogenase were measured. Intoxication of rats with cadmium for three months resulted in a reduction of glycolytic enzymes in the serum, ST and FTa muscle fibers and in the liver but did not change the activities of glycolytic enzymes in the FTb muscle fibers. The data obtained for the concentrations of glycogen in the liver and skeletal muscles suggest different mechanisms of cadmium influence on glycogen utilization in these organs.

[The effect of cadmium poisoning on glucose transformation in skeletal muscles]. / Der Einfluss der Cadmiumintoxikation auf den Glucoseumsatz in Skelettmuskeln.

Long-time effects of Cd on carbohydrate metabolism were investigated in male Wistar rats. A dose of 0.3 mg/kg body weight of Cd in acetate form was subcutaneously injected to the experimental animals twice a week through 3 months. Selected enzyme activities of glycolysis as well as concentrations of glycogen, glucose, pyruvate, lactate, triglycerides, and free fatty acids (FFA) were determined in blood serum, muscles, liver, and fatty tissues. The experimental animals differed from the control group, in that Cd intoxication was followed by decline in the blood serum only of pyruvate kinase and lactate dehydrogenase activities. In the liver, however, all enzyme activities were reduced. Glycogen glucose and FFA levels were increased. Intramuscular alterations were found to depend on the fibre type. The severest disturbance of glycolysis was recordable from red long fibres, whereas rapid white fibres were more resistant. The change in FFA concentration may be interpreted as some compensation for the impairment of carbohydrate metabolism in the energy balance.

Metabolic adaptation of muscles to exercise, vibration and raised temperature under the influence of cernitins.

Wistar rats were used to study the effects of cernitins, i.e. aqueous and oil extracts of pollens, on the metabolic adaptation of the soleus muscle to exercise, vibration and raised ambient temperature. The animals were exposed to selected combinations of these factors for 5 days during 1.5 hour daily. A part of the animals was given orally cernitins in daily doses of 6 mg/kg of body weight for 10 days before the exposure. Among the adaptation changes studied in the soleus muscle, 24 hours after the last exposure, cernitins caused: a reduction of the amount of total protein, an increase in the proportion of soluble proteins in the protein fraction, an increase in the tissue oxygen consumption, an increase of already elevated pyruvate kinase activity, a further rise in ATP level, an increase in lactic dehydrogenase activity, a rise in the activity of cholinesterases. Moreover, it increased significantly the body weight and the weight of the studied soleus muscle. Cernitins, in combination with certain types of exposure used in this experiment, exerted a catabolic action, increased the rate of anaerobic metabolism and enhanced adaptation to exercise, vibration and temperature. The direction of the adaptation changes depended on the type of exposure to environmental factors.

Specific problems of physical training of cosmonauts.

Physical fitness and--closely related to it--physiological aspects of physical condition are very important in the elevation of the tolerance level to harmful effects of surrounding factors. To improve the possibilities of withstanding the factors of spaceflight, the cosmonauts undergo special training. Among the training methods there is a physical training program that is planned in relation to the general fitness of the cosmonaut. The following problems will be discussed, based on results obtained by the Polish Institute of Aviation Medicine: 1) The specific future of a physical training program. 2) The results of physiological research in a specifically elevated tolerance level to hypoxia and acceleration. 3) The possibilities of extension of physical training taking into account other flight factors.