The effect of intermittent hypoxia with different degrees and frequencies on levels of superoxide dismutases and malondialdehyde in vascular endothelial cells

Abstract

To investigate the effect of degree and frequency of intermittent hypoxia on level of superoxide dismutase (SOD) and malondialdehyde (MDA) in vascular endothelial cell. We used umbilical vein endothelial cell ECV304 to set up cell model. The experiment cell strains contained one control group and eight experimental groups. We exposed cells by 3 different degree and 5 different frequency intermittent hypoxia gas separately as experimental groups, and the cells exposed to normal air as a control group. We determined levels of SOD and MDA by the way of ELISA in cytoblastema. The level of MDA of three different degree intermittent hypoxia groups were higher than the level in the control group (P < 0.01). The level of SOD in three different degree hypoxia groups is lower than the level in the group (P < 0.01). The level of SOD was decreased and the level of MDA was increased gradually with the decreasing of hypoxia degree (P < 0.01). There is a trend as the level of MDA and SOD increased and decreased with frequency decreased. The level of MDA was no different between the group of frequency in 40 per hour and 20 per hour (P > 0.05). When hypoxia frequency decreased, the level of MDA increased, and the level of 9.2 per hour exposure group was the lowest, but the level of MDA decreased again when the frequency was reaching 6.3 per hour (P < 0.01). When hypoxia frequency decreased, the level of SOD decreased, and the level of 9.2 per hour group was the highest, but the level of SOD decreased again if the hypoxia frequency was reaching 6.3 per hour (P < 0.01). The level of SOD was negative correlated to that of MDA under different hypoxia degree exposure (r = 0.932, P = 0.000), and the level of SOD was negative correlated to that of MDA under different frequency exposure (r = 0.832, P = 0.000). The intermittent hypoxia activates oxidative stress reaction in endothelial cells, and that induces the increasing of reactive oxygen species, and the antioxygen capacity become weaker. The decreasing and increasing of oxidative stress reaction depends on the degree of hypoxia and, is correlated to the frequency of hypoxia. Exposed to intermittent hypoxia, the balance of oxidative stress reaction and antioxygenative system of endothelial cell was disturbed.