[en] 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 to 7 times this value. This finding is also documented by the increase in the ratio of the ⁸⁵Sr concentration in the heart and the blood. The increase observed in ⁸⁵Sr accumulation in the myocardium is comparable to repeatedly described changes accurring in radioactive calcium after the administration of isoprenaline. (author). 2 tabs., 9 refs

[en] The study was aimed at establishing whether administration of toxic doses of isoproterenol increases the accumulation of strontium - a homologue element of calcium - in the rat heart during postnatal development. It has been shown that in 14-day-old animals, ⁸⁵Sr uptake was not increased; starting from the 30th day of postnatal life this parameter increased significantly up to adulthood. (author) 3 figs., 13 refs

[en] Radioselenium concentration and excretion was studied after administration of ⁷⁵Se-labelled selenite to male rats during ontogeny. The concentration of radioselenium in individual organs decreases with increasing age. The largest differences between young and adults were in the quantity and quality of excreted substances. During 2 h after the administration of 20 μmol selenite/kg young rats excreted 2.4% of the dose, essentially in the urine only, whilst adults excreted a total of 11%, distributed equally in breath and urine. The part excreted as methylated metabolites was 0.1% of the administered dose in young and 6.3% in adult rats. These results support the hypothesis that the differences in the sensitivity to the toxic action of selenite between young and adult rats can be due to ontogenic differences in selenium metabolism. (orig.)

No abstract available

[en] The organ concentration, excretion and excreted forms of selenium were studied in young and adult rats after a single subcutaneous injection of a sublethal dose of ⁷⁵Se-selenite. In the young, about a 10-fold higher concentration of ⁷⁵Se in the blood, liver kidneys and heart was found at all the experimental intervals studied (1 to 7 days). The highest ⁷⁵Se concentration in the young was in the liver while in the adults it was found in the kidneys. The spectrum of radioselenium metabolites in the urine was similar in both groups. However, the main product excreted by young rats was ⁷⁵Se-glutathione selenotrisulfide and an unidentified neutral substance while it was the trimethylselenonium ion in the adults. Ontogenetic differences in the selenium metabolism could be one of the factors underlying the differences in the response of the young and the adult rats to toxic doses of selenite. (author). 2 tabs., 9 refs

[en] The uptake of radioselenium in various eye tissues of 14 day old and adult laboratory rats was followed 2 h after subcutaneous injection of ⁷⁵Se-selenite. In comparison with adult rats, the radioselenium uptake in all eye tissues of the young was significantly higher. The greatest difference between the two groups was found in the specific radioactivity of the tissues forming the anterior segment of the eye (more than 300 times), the lowest one in the retina (roughly 60 times). Electrophoresis showed the same spectrum of selenium metabolites in aqueous humour as in other body fluids, albeit in different proportions. The higher selenium uptake in the crystalline lenses of the young apparently reflects age-dependent differences in the structure and function of membranes and system barriers and could thus he one of the factors contributing to the formation of selenium cataract in young rats. (author)

No abstract available

No abstract available

[en] The effect was observed in vitro of selenite on the uptake of ⁸⁶Rb by the lens in two weeks old and adult rats. Also measured was the uptake of ⁸⁶Rb by the lens in vitro in 30-days old rats with cataracts induced by the administration of selenite at day 14 after birth and in control animals of the same age. Selenite in a concentration of 0.4 mM and more caused an insignificant decrease in ⁸⁶Rb uptake by the lens in adult rats while in the lens of young rats the uptake decreased significantly already at concentrations lower by two orders. Lenses with cataracts took up significantly less ⁸⁶Rb than transparent lenses; body weight, the weight of the fresh lens and its dry mass decreased while the water content in the lens was higher as compared with control groups. (author). 2 tabs., 26 refs

[en] One of the factors important for the maintenance of eye lens transparence is its water content which is controlled by the active transport of Na⁺ and K⁺ in the lens epithelium. In early phases of ontogenesis the rat lens is highly sensitive to various cataractogenic impulses (e.g., selenium induced cataract). In the present study, the question was studied of whether the ion turn-over in the lens changes during ontogenesis. Experiments were done on Wister rats of age span from 1 prenatal day to 2 years. The uptake was measured of ⁸⁶Rb which in the lens is transported analogously to K⁺. The rats were decapitated and extracted lenses were incubated in a MEM medium supplemented with bovine fetal serum and ⁸⁶Rb. ⁸⁶Rb uptake was expressed as a ratio of ⁸⁶Rb concentration in lens water to its concentration in the medium at the beginning of incubation. The ⁸⁶Rb was found to differ substantially in different age groups. A rapid drop in the uptake of ⁸⁶Rb was found in the lens in the critical period of lens development when the lens grows intensively and displays the highest sensitivity to exogenous metabolic disturbances. The developmental changes in the uptake of ions by the lens can reflect changes in the synthesis of both enzymes and crystallines. (author)