We investigated metabolic changes in human umbilical venous endothelial cells, when these were incubated under hypoxic followed by hyperoxic conditions, thus simulating
hypoxia and reoxygenation. The human umbilical venous endothelial cells were incubated with a degassed
buffer (
oxygen content: 0-0.5%) for either 3 h or 24 h, followed by a 60 min incubation with
oxygen-perfused
buffer (
oxygen content: 100%). Three hours of
hypoxia led to a slight decrease in the
ATP and
creatine phosphate content (-16% +/- 5%), while a pronounced decrease of high energy
phosphates (-54% +/- 4%) was observed after 24 h of
hypoxia. Reoxygenating the cells after 3 h of
hypoxia led to restoration of the content of high energy
phosphates, while reoxygenation after 24 h resulted in a strong decrease (-66% +/- 4%). The
prostaglandin I2 release during the first 3 h of
hypoxia exceeded the release in the following 21 h. In all cases, reoxygenation increased the
prostaglandin I2 release. Under normoxic conditions the ratio between oxidised
glutathione and
reduced glutathione shifted from 1:100 to 1:4.5 after 3 h of
hypoxia. The content of lipid peroxidation products was almost unaffected during
hypoxia, whereas reoxygenation resulted in a pronounced increase (+380% +/- 60%). The results of this in vitro study suggest that relatively long periods of
hypoxia lead to a deficiency of high energy
phosphates in the cell. Reoxygenation leads to the formation of
oxygen-derived radicals, irrespectively of a prior
hypoxia.