A study of rat liver oxidative stress injury with different frequencies intermittent hypoxia and the effect of Tempol

Abstract

Objective To study the effect of different frequencies intermittent hypoxia on malondialdehyde (MDA),superoxide dismutase (SOD) and total antioxidant capacity (T-AOC)of rat liver and to investigate the effect of Tempol.Methods To establish a chronic intermittent hypoxia (CIH)animal model in rats,in order to mimic the intermittent hypoxia/reoxygenation (IH/ROX) of obstructive sleep apnea syndrome in humans.56 healthy male Wistar rats were randomly assigned to seven groups:4different IH frequencies groups (IH1:10 times/h,IH2:20 times/h,IH3:30 times/h,IH4:40 times/h with 5 ％ O2 ),the I H3+Tempol group (30T group),the IH3 +normal saline control group (30N group)and normoxia control group (NC group),each group of eight rats.After the experiment,we measured the levels of MDA,SOD and T-AOC in rat liver homogenate.Results The level of MDA in 4 different IH frequencies groups was higher than in NC group (all P ＜0.05),the activity of SOD,T-AOC were lower than in NC group (all P ＜0.05).And there was a trend as the IH frequency increased,the level of MDA was gradually increased,the activity of SOD and T-AOC were gradually decreased.The differences of MDA,SOD,T-AOC level were statistical significant between each two different IH frequencies groups (all P ＜0.05),except the differences between IH3 group and IH4 group (all P ＞0.05).Compared with IH3 group,30N group,the level of MDA in 30T group was decreased ( P ＜0.05),the activity of SOD,T-AOC were increased (all P ＜0.05),an＞ the levels of MDA,SOD,T-AOC in 30T group were not significant with in NC group (all P ＞0.05).The level of MDA in 4 different IH frequencies groups was negative correlation with the activity of SOD,T-AOC ( r were -0.721,-0.653 respectively,all P =0.000).Conclusions Different CIH frequencies had different degrees of injury of oxidative stress on rat liver,but the relationship between the degree of injury on liver and the CIH frequencies was not entirely a linear.Tempol could prevent the oxidative stress injury on the rat liver of CIH. Key words: Intermittent hypoxia; Oxidative stress; Obstructive sleep apnea syndrome; Tempol