Hydrogen peroxide (H2O2) production in exhaled air was measured in ventilated preterm newborns at 5, 24 and 48 hours after delivery, using originally designed method of exhaled breath condensate (EBC) collection. H2O2 production in expired gas was 812±34 pmol/20 min during the first measurement and then declined to 389±21 at 24 hours and 259±26 pmol/20 min at 48 hours.
We studied the extent to which hormonally-induced mitochondrial glycerophosphate dehydrogenase (mGPDH) activity contributes to the supply of reducing equivalents to the mitochondrial respiratory chain in the rat liver. The activity of glycerophosphate oxidase was compared with those of NADH oxidase and/or succinate oxidase. It was found that triiodothyronine-activated mGPDH represents almost the same capacity for the saturation of the respiratory chain as Complex II. Furthermore, the increase of mGPDH activity induced by triiodothyronine correlated with an increase of capacity for glycerophosphate-dependent hydrogen peroxide production. As a result of hormonal treatment, a 3-fold increase in glycerophosphate-dependent hydrogen peroxide production by liver mitochondria was detected by polarographic and luminometric measurements.
High temperature can change the effects of intra- and intercellular regulators and therefore modify the cellular response to hypoxia. We investigated H2O2 production by alveolar macrophages, isolated from adult male rats, which were incubated under conditions of oxygen deficiency and high temperature (experiment in vitro). The incubation of these cells for 2 hours at 10 % or 5 % oxygen led only to slight fluctuations in the H2O2 level, while the rise of temperature from 37C up to 42C significantly increased its generation. Level of thiobarbituric acid-reactive substances (TBARS) underwent similar changes. Under these conditions the accumulation of H2O2 was found to be caused mainly by its decreased cleavage rather than its enhanced production. This is indicated by decreased catalase and glutathione peroxidase activity together with a parallel absence of significant changes in superoxide dismutase (SOD) activity. Slight fluctuation of reduced glutathione level and the pronounced increase of glucose-6-phosphate dehydrogenase (G6PD) activity were detected. Strong (5 %) but not moderate (10 %) lack of oxygen led to a sharp increase in formation of cellular nitrite ions by alveolar macrophages. In general, our data showed that high temperature did not lead to any qualitative shifts of defined hypoxia-derived changes in oxidant/antioxidant balance in alveolar macrophages, but promoted sensitivity of cells to oxygen shortage.