Abstract

Heavy metals tend to occur in increasingly many aspects of human activities. Studies of cadmium (Cd) have revealed that it is extremely toxic in its effects. It is known that selenium (Se) may suppress deleterious effects of Cd. We investigated the effects of dietary Cd-intoxication on the incorporation of precursors of RNA, protein and ANP (atrial natriuretic peptide) granule synthesis in mouse cardiocytes and compared them with the results of Se interaction with Cd-intoxication. Functional condition of the heart was evaluated on the basis of the number of ANP granules synthesized in cardiocytes of the right atrium in the mice exposed to the tested elements. The experiment was conducted on 100 male white Balby mouse during the period of three months. The animals were divided into four groups. The control group I (C) was fed a standard Murigran diet. Group II (Cd) - received 50 ppm Cd as cadmium acetate in drinking water. Group III (Se) received a standard diet supplemented with 5.0 mg Se/kg DM/24 h as acid sodium selenate. The experimental animals in group IV (Cd + Se) - were fed a diet supplemented with Cd and Se in the same amounts as the above groups. Our results revealed that after 3 months long intoxication with Cd, 3H-uridine and 3H-alanine uptakes to cardiomyocytes were decreased by 33% and 40%, respectively, and fewer ANP granules were synthesized when compared with the controls. Ultrastructure of myocytes proved slightly distorted. Se-intoxicated cardiomyocytes indicated diminished incorporation of RNA synthesis precursors by 17% and 27% in the ventricle and atrium, respectively, in comparison with the controls. Some Se-induced structural changes were observed. Finally, after Se in interaction with Cd intoxication, the uptake of 3H-uridine and 3H-alanine to cardiocytes was higher and the number of ANP granules increased. The values approximated those in the controls. We concluded that: prolonged Cd intoxication disturbed intercellular metabolism by damaging ultrastructural elements and suppressing the incorporation of precursors of RNA, protein and ANP granule synthesis. Se in interaction with Cd revealed protective effects against Cd toxicity. After Cd-Se-intoxication neither metabolic activity nor cardiocyte ultrastructure showed significant differences from those in the controls.
key words: cadmium, selenium, heart, nucleic acids, proteins, ANP (atrial natriuretic peptide)

Keywords: ANP (atrial natriuretic peptide), Nucleic Acids, Proteins, Selenium, Cadmium