V Baláz’s research while affiliated with Welding Research Institute - Industrial Institute SR and other places

Male Wistar specific-pathogen-free rats aged 2, 7, 17, 30, 60, 120, 200, 360 and 600 days, all killed in experiment on the same day, were examined. The body weight significantly increased until the 200th day, the weight of adrenals until the 120th day and the adrenal protein content until the 30th day of life. The adrenaline content of the adrenals increased continuously during the 600 days studied. Adrenal noradrenaline content increased rapidly over the first 17 days, remained at a stable level until the 120th day, and rose to a higher level after 200 days. The activity of adrenal catecholamine-synthesizing enzymes also increased with age: tyrosine hydroxylase gradually increased until the 360th day, dopamine-beta-hydroxylase and phenylethanolamine-N-methyl transferase until the 200th day. Our results demonstrate that, in the rat, during development there is a gradual increase of adrenal weight, adrenaline content, tyrosine hydroxylase and phenylethanolamine-N-methyl transferase activity until maturation (120th day), whereas the adrenal noradrenaline content reaches the adult values earlier, around the 17th day. During aging, adrenal catecholamines significantly increase when compared to young-adult rats (120-day-old), probably due to the elevated activity of the adrenal catecholamine-synthesizing enzymes. The increased adrenal catecholamine levels in old animals might be connected with a higher incidence of cardiovascular diseases in aged.

Changes in the activity of cholinesterase in the heart muscle and liver of the Norway rat in the course of a 24 hour rhythm are reported. In the heart the activity reaches maximum at 7.30 a m, and minimum at 7.30 p m, whereas in the liver maximum activity is at 1.30 p m, and minimum at 10.30 p m. Humoral stress through a change of adrenalin, histamine, triiodothyronine and cortisol causes a decrease in the activity of cholinesterase, which is significant in the liver. The action of humoral stress in a twenty four hour rhythm is more efficient in the night phase than in the day phase.

The effect of a 6 wk period of acclimatization upon the energetic and anabolic functions of cells was studied at altitudes of 350 and 1,350 m above sea level. Attention was given to changes in amounts of studied metabolic substrates under control conditions, then after the administration of adrenocorticotropic hormone (5 U per kg) and after exposure to hypoxia at the altitude of 6,000 m above sea level in a barometric chamber for 6 hr, and to the statistical changes during acclimatization. A significant activation of the anabolic functions of cells was found after the acclimatization, i.e. as a response to hypoxia. Myocardial RNA was especially significantly increased with a difference in altitude by 1,000 m. The conclusion was arrived at that due to acclimatization of the body, the protein synthesizing mechanism becomes activated under hypoxic conditions.

Levels of ninhydrin positive compounds (amino acids and peptides) were studied in the heart muscle, liver and brain of rats acclimatized for 3 mth at 1,350 m above sea level. Compared to a control group of animals kept at 350 m above sea level increased activity of protein synthesis was evident in the heart muscle and brain as documented by the incidence of several new peptidic fragments as well as an increase in the number of individual bands in rats acclimatized to high altitude.