In Vitro Effects of Hypoxia and Reoxygenation on Human Umbilical Endothelial Cells

Abstract

Summary: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 24h, followed by a 60min 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 I 2 release during the first 3 h of hypoxia exceeded the release in the following 21 h. In all cases, reoxygenation increased the prostaglandin I 2 release. Under normoxic conditions the ratio between oxidised glutathione and reduced glutathione shifted from l : 100 to l : 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.

Hypoxia primes endotoxin-induced tissue factor expression in human monocytes and endothelial cells by a PAF-dependent mechanism

“…Such an effect which occurred in a time-dependent manner could be attributed to the generation of PAF since it was blocked by SR 27417, a potent PAF receptor antagonist (Herbert et al, 1991). This effect can be compared to what has been previously shown in other experimental systems such as modulation of endothelial cell adhesiveness where hypoxia has also been shown to increase neutrophil or granulocyte adhesion to activated endothelial cells through a PAF-dependent pathway Arnould et al, 1993;Pietersma et al, 1994;Budd et al, 1990;Norisama et al, 1992;Windischbauer et al, 1994). Moreover, the kinetics of this effect well correlated with PAF kinetics production by HUVEC under hypoxia (Arnould et al, 1993).…”

Adaptation of chondrocytes to low oxygen tension: Relationship between hypoxia and cellular metabolism

“…Although hypoxia is linked to thiol metabolism, in a number of tissues, it has been shown that a decrease in oxygen tension results in variable effects on the glutathione concentration (Johnson et al, 1993;Windischbauer et al, 1994;ODwyer et al, 1994). In contrast to those studies, we found that hypoxia caused a fall in the glutathione content of cultured chondrocytes.…”

Anti‐inflammatory activity of creatine supplementation in endothelial cells in vitro

“…It is highly possible that the PC energy system is active in endothelial cells, based on the fact that a few reports demonstrated that endothelial cells of umbilical veins contained PC (Loike et al ., 1992; Windischbauer et al ., 1994). However, those previous reports did not show intracellular CR levels or the role of CR in endothelial cells.…”

“…The PC energy system and CR supplementation have been extensively investigated in muscle cells, but not in endothelial cells. To our knowledge, there have been only a few reports on the presence of PC and ATP in endothelial cells (Loike et al ., 1992; Windischbauer et al ., 1994). It remains to be elucidated whether CR supplementation may influence the cell functions of endothelial cells.…”