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Biomedical subjects

A A Viru

Publications and source records attributed to A A Viru.

At least 19 recordsLinked to original sources
PubMed1985

[Recovery after prolonged muscular work].

Increased protein, tyrosine and 3-methylhistidine content has been observed in the skeletal muscles of rats 2-24 h after a 10-hour swimming period. This was accompanied by a significant rise in 3-methylhistidine excretion during the second day of the recovery period. Such combination of alterations suggests simultaneous augmentation of both protein synthesis and decomposition in the muscles after active work. The start of the alterations coincides with post-exercise increase of blood corticosterone level (2-6 h after work) and with the achievement of glycogen supercompensation in the liver and muscles.

Animals↗
PubMed1984

[Interrelation between corticotropin and cortisol during static physical loading].

The time-course of changes in the blood corticotropin and cortisol concentration was studied in 9 dogs during standing with a load on the back. The pituitary-adrenocortical system was shown to be activated fairly rapidly. The initially occurring rise in corticotropin concentration was coupled with a more prolonged elevation of blood cortisol. In the absence of cortisol from the blood which was caused by long-term injection of chloditan, activation of corticotropic function proceeded more intensely whereas the reduction in corticotropin concentration after its initial increment was less demonstrable as compared to that seen in normal adrenal function.

Adrenocorticotropic Hormone↗
PubMed1984

[Protein metabolism in the muscles after work].

The 20-hr swimming increased the contants of protein, thyrosine and 3-methylhistidine (also per 1 g of protein) in skeletal muscle of rat within 2-24 hrs. A significant increase in 3-methylhistidine excretion followed this on the 2nd day of the recovery period. The revealed combination of changes suggests a simultaneous augmentation of both synthesis and disintegration of protein in muscles after their activity. Hence, the increased excretion of 3-methylhistidine during recovery period reflects an intensive renewal of the molecular content of proteins of actinomyosine complex. The 3-methylhistidine level in intestine increased only for a short time and seems not to contribute to the delayed increase in excretion of the amino acid.

Animals↗
PubMed1981

[Role of the thyroid gland in skeletal muscle adaptation to increased motor activity].

Experiments in 16-week old male Wistar strain rats showed that deficiency of thyroid hormones caused a decrease of cytochrome aa3, RNA, myofibrillar and sarcoplasmic protein contents in m. quadriceps femoris, Mg2+ activated actomyosin ATPase activity and physical working capacity of untrained and trained animals also reduced. Physical activity the intensity of which corresponded to metabolic power output of 190%. Vo2max stimulated thyroid function, elicited a significant elevation of blood thyroxine level, oxidative potential and intensity of protein synthesis in m. quadriceps femoris, the character of these changes depending on the type of muscle fibers. The stimulation of thyroid function caused an elevation of muscle content of cytochrome aa3 and content of RNA, especially in the glycolytic fibers of hypothyroid rats.

Adaptation, Physiological↗
PubMed1979

[Participation of glucocorticoids in development and provisions for work capacity].

Physical working capacity of the adrenalectomized Wistar rats can be augmented to some extent by training. This is not accompanied by increased unspecific resistance or augmented content of liver glycogen. The trained adrenalectomized rats revealed heart hypertrophy and increased activity of Mg2+-activated actomyosine ATPase in myocardium. After the training the physical worcing capacity was lower in adrenalectomized rats than in thyroidectomized ones. The 5-day administration of hydrocortisone failed to increase swimming time in adrenalectomized rats provided a high dose of progesterone was injected simultaneously. This can be due to the competition between progesterone and glucocorticoids for the glucocorticoid cytoplasmic receptor sites. The data obtained suggest that the effect of glucocorticoids on the physical working capacity is associated with their action on the adaptive protein synthesis.

Adrenal Glands↗
PubMed1978

[Changes in the adrenal cortex during adaptation to different regimes of motor activity].

The hypertrophy of the adrenal glands was higher in the rats adapted to long-lasting exercises of moderate and mild intensities. Ultrastructural analysis showed that there were more mitochondria and vesicular cristae as well as the elements of cytoplasmatic reticulum and lipid droplets in the cells of adrenal cortex of the adapted rats. The data obtained suggest two types of adaptational changes in the adrenal cortex: 1) pronounced hypertrophy with low spontaneous functional activity and increased content of cytochrome a--a3; 2) less pronounced hypertrophy with higher content of corticosterone and lower content of cytochrome a--a3 in adrenals.

Adaptation, Physiological↗
PubMed1976

[Adrenocortical regulation of protein metabolism during prolonged physical stress].

Experiments on Wistar male rats revealed depression of labeled amino acid incorporation into the tissue proteins as a result of swimming. When prolonged swimming was accompanied by an enhanced adrenocortical activity the block of the protein synthesis in the liver proved to disappear. Adrenalectomy excluded the activation of alanine-aminotranspherase and a drop of the free amino acids in the liver during physical exercise: corticosterone administration to adrenalectomized animals restored these shifts.

Adrenalectomy↗
PubMed1976

[The role of adrenocortical response to physical stress on the body's work capacity].

Adrenocortical reaction to muscular exertion was inhibited by the intramuscular injection of 125mg of dexamethasone for 2 days of every week of the training. The maximal swimming time in the water (33--34 degrees C) with an additional load of 3 per cent of body weight failed to increase after 5 weeks of training in the animals to which dexamethasome was infected. In these animals the blood corticosterone level increased less after the maximal swimming test than in rats trained without any dexamethasone administration.

Adrenal Cortex↗
PubMedDate not supplied

[Effect of triathlon competition on the content of various hormones and the energy substrate of the blood].

The effect of triathlon (3.8 km swimming, 180 km biking, 42 km running) and of its short variant (1.5 km swimming, 42 km biking, 14 km running) was studied in 7 and 14 well-trained men, respectively. The level of plasma glucose, total cholesterol, HDL, LDL did not change significantly during the competition. FFA concentration increased significantly (by 439 and 61%, respectively). Triglycerides concentration decreased during the prolonged variant. Both variants of triathlon caused a pronounced rise in the cortisol level and moderate increase in somatotropin and progesterone levels. Testosterone concentration increased during a short variant and decreased during a prolonged one. Insulin and C-peptide levels decreased. All those changes in hormones concentration are consistent with an increased lipolytic activity and, may be, with increased glycolytic activity (maintenance of the normal glucose concentration in blood). The rise in the aldosterone level reflects the homeostatic activity in maintaining electrolyte balance.

Adult↗
PubMedDate not supplied

[Relation between changes in the blood levels of beta-endorphin and various hormones during physical exercise].

Dynamics of beta-endorphin, corticotropin, cortisol, somatotropin, insulin and triiodothyronine content were studied using bicycle ergometer in blood of 22 persons during 2 hrs exercises. After an initial increase the beta-endorphin content was subsequently decreased. At the same time, the decrease in the neuropeptide content was accompanied by repeated elevation within the second hr of the exercise, mainly in persons exhibiting high working capacity, while in other persons the hormone concentration decreased below the initial level at the end of the exercise. These alterations in the content of beta-endorphin correlated distinctly with dynamics of pituitary-adrenocortical hormones variation. In untrained persons the initial increase in beta-endorphin content was especially distinctly related to the elevation in somatotropin and to a decrease in insulin content in blood. Concentration of triiodothyronine in blood was altered independently of the alterations of other hormones.

Adolescent↗