[Heavy metal poisoning in relation to glucose-6-phosphate dehydrogenase activity in sheep erythrocytes]. / Intoxikácia tazkými kovmi vo vztahu k aktivite glukóza-6-fosfát dehydrogenázy v erytrocytoch oviec.

Peroxidative lesions of cells and production of free radicals from endo- and exogenous reasons, eg. due to air pollution, can result in severe lesions of cells and subsequent pathological processes (Rieger, 1992; Robbins and Cotran, 1988). A pentose cycle plays an important role in the system of antioxidative protection: glucose-6-phosphate dehydrogenase (G-6-PD; EC 1.1.1.49) is its first enzyme. G-6-PD activity was evaluated in the erythrocytes of sheep kept in the region contaminated by heavy metals with mercury dominating among them, and in the same animals after administration of a feed mixture containing Hg, Pb Cd, Zn Cr, Cu, Fe and As (Fig. 1). Boehringer Mannheim test was used to determine the G-6-PD activity. There was no significant differences in the enzyme activity in the sheep from a contaminated region and in the animals outside the air-pollution region (control animals) before the applications of heavy metals started. The average value of G-6-PD activity was 13.96 +/- 0.94 mU.10 (-9) Ec in control animals and 14.39 +/- 1.49 mU.10 (-9) Ec in the animals from a contaminated region. After eight-day applications of heavy metals the G-6-PD activity increased statistically significantly to 18.71 +/- 2.45 mU.10 (-9) Ec; P < 0.01, and to 23.55 +/- 1.87 mU 10 (-9) Ec after 16 days of application; P < 0.001 (Fig. 2). An increase in G-6-PD activity after heavy metal applications is probably a compensation mechanism in the system of erythrocyte antioxidative protection due to higher peroxidation. The long term increased intake of heavy metals from polluted air did not lead to any rise of G-6-PD activity probably due to the lower dose of heavy metals and/or to adaptation of animal organisms to long run emission exposure. The results demonstrate that G-6-PD can be one of the biochemical indicators at organism load by heavy metals with mercury dominating among them.

Modifications of the electrical activity in the ventromedial hypothalamic nucleus and the lateral hypothalamic area of 24-hour food-deprived rats.

The amplitude of the electrical activity of the ventromedial hypothalamic nucleus (VMH) and lateral hypothalamic area (LH) was evaluated in rats after 24-hr food deprivation to determine the effects of the diet they had received before fasting. Bioelectrical potentials were registered by means of monopolar electrodes. In rats after 24-hr food deprivation an increase in the absolute values of the amplitude of the electrical activity of the VMH and LH was found; this effect was more pronounced in the LH. Comparing the amplitude of the electrical activity of the VMH and LH, we found it to be always higher in the VMH in ad libitum fed rats, while in 24-hr food-deprived rats the electrical activity was always higher in the LH. The extent of changes depended on the diet the rats had received before fasting--they were most marked in rats fed on a high-protein diet and less marked in rats fed on either a standard or a high-fat diet before food deprivation.