The aim of this study was to assess the effects of L-cysteine (Cys) (7 mg/kg) and N-acetyl-L-cysteine (NAC) (50 mg/kg) in the rat liver caused by subchronic i.p. application of methionine (Met) (0.8 mmol/kg) during 21 days. Malondialdehyde (MDA) concentration, glutathione content (GSH), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and acetylcholinesterase (AchE) activities were determined in the liver tissue and activities of liver enzymes (AST, ALT, ALP, and GGT) and concentrations of total proteins and albumin were determinated in plasma/serum. Catalase, superoxide dismutase, and acetylcholinesterase activities were increased by Cys and NAC. Met caused periportal mononuclear infiltration and rare focal necrosis of hepatocytes. In Cys- and NAC-supplemented groups, intracellular edema and microvesicular fatty changes without necrosis were noticed. We observed decrease of AST, ALT, and ALP activity in the methionine-treated group. Our results indicate that Cys and NAC application can increase activity of antioxidative enzymes and prevent intensive histological changes in liver in condition of subchronic methionine exposure.

The aim of this study was to investigate the effects of acute and repeated immobilization stress on oxygen consumption (QO2) of the isolated interstitial rats' testes cells (ISC). The oxygen consumption by ISC testes was measured in vitro with a Clark-type oxygen electrode. Acute immobilization stress (2 h) induced decrease in QO2 (-49% V4, -31% V3) which was statistically significant (p<0.01). Repeated immobilization stress (2 hours daily for 10 consecutive days) induced a fall in QO2 (-10% V4, -4% V3) but this inhibition of respiration was not statistically significant (p>0.05). The mechanisms by which immobilization stress induces mitochondrial dysfunction as well as mechanisms which develop an adaptive response to repeated immobilization remain unclear, so that further investigations of this mechanisms are required.

In our previous work we have shown that in mouse heart basal level of endothelial produced nitrite, as a marker of nitric oxide (NO) formation, was 9.7 nmol l(-1). Bradykinin (10 microl l(-1)) induced a 5-fold rise in nitrite release, the coronary venous effluent concentration being 58 nmol l(-1), but there was no effect on myocardial oxygen consumption (MVO2). The aim of this study was to assess the levels of authentic nitric oxide solution, exogenously applied, on myocardial oxygen consumption. Isolated mouse hearts (n=36) were paced (500 imp./min) and perfused at constant flow (16.0 +/- 0.3 ml g(-1) min(-1)). When coronary vasculature resistance was carefully controlled by adenosine (1 micromol l(-1)), authentic nitric oxide solution, in a concentration less than 5 micromol l(-1) did not alter myocardial oxygen consumption. Only concentrations of nitric oxide higher than 5 micromol l(-1) induced reduction in myocardial oxygen consumption. Thus in the saline perfused mouse heart, with carefully controlled vasodilatation, modulating myocardial nitric oxide levels using an arterial application of authentic nitric oxide, concentrations higher than 5 micromol l(-1) of nitric oxide were required to induce a decrease in myocardial oxygen consumption.