Effects of hyperbaric oxygen pretreatment on hemodynamics and cytokines in rats with acute hypoxia

Abstract

Objective To observe the effects of hyperbaric oxygen (HBO) pretreatment on hemodynamics and such cytokines as IL-6,IL-10 and TNF-α in rats with acute hypoxia (at an altitude of 7 000 m).Methods Fifty SD rats were randomly divided into 6 groups:the HBO groups [the HBO group Ⅰ (n =10),Ⅱ (n =10) and Ⅲ(n =10)] and the control groups [the control group Ⅰ (n =6),Ⅱ (n =7) and Ⅲ (n =7)].The animals in the HBO groups were pretreated with HBO for 7 days,while the animals in the control groups received no treatment.The HBO pretreated animals and the animals in all the control groups were exposed to hypobaric pressure at an altitude of 7 000 m for a duration of 12 h,24 h and 72 h respectively.At different time points,the rats in all the groups had abdominal anesthesia with 10％ urethane in the hypobaric chamber,and then a cardiac catheter was inserted via the right external jugular vein into the right ventricle and pulmonary artery.Multi-channel polygraphy was used to monitor the 5-min pulmonary artery pressure curve,the pulmonary artery pressure (PAP),the right ventricular systolic pressure (RVSP) / left ventricular systolic pressure (LVSP),the right diastolic blood pressure (RVEDP) / the left diastolic blood pressure (LVEDP),the right ventricular systolic ventricular isovolumic maximum rate of pressure rise and right ventricular diastolic ventricular isovolumic maximum rate of pressure drop (± dp / dtmax) and other hemodynamic parameters.Blood samples were collected to detect serum levels of interleukin-6 (IL-6),interleukin-10 (IL-10) and tumor necrosis factor-α (TNF-α),SOD and MDA.Results (1) The RVEDP in the animals of the HBO group Ⅰ was decreased with significant difference,when it was compared with thab of the control group Ⅰ (P ＜ 0.05).The mPAP,RVEDP,-dp/dtmax for the animals in the HBO group Ⅲ were decreased,also with significant difference,when they were compared with those of the control group Ⅲ (P ＜ 0.05).The mPAP and ± dp/dtmax for the animals in the HBO group Ⅱ were decreased with significant difference,when they were compared with those of the HBO group Ⅰ (P ＜ 0.05 or P ＜ 0.01).The RVSP,RVEDP ± dp/dt mPAP in the animals of the HBO group Ⅲ was lower than that of the HBO group Ⅱ with very significant difference (P ＜ 0.01).(2) The LVEDP in the animals of the HBO group Ⅰ was lower than that in the animals of the control group Ⅰ,with significant difference(P ＜0.05).The LVEDP in the animals of the HBO group Ⅲ was lower than that in the animals of the control group Ⅲ,with very significant difference(P ＜0.01).The LVEDP in the animals of the HBO group Ⅱ was increased with significant difference(P ＜0.05),the LVSP and RVEDP in the animals of the HBO group Ⅲ was also increased with significant difference (P ＜ 0.05 or P ＜ 0.01),when they were compared with those of the HBO groud Ⅰ.(3) The SOD level in the animals of the HBO group Ⅰ was higher than that in the animals of the control group Ⅰ,with significant difference,while the levels of IL-6,IL-10 and TNF-α were lower than those of the control group Ⅱ,also with significant difference(P ＜ 0.05 or P ＜ 0.01).The SOD level in the animals of the HBO group Ⅱ was higher than that in the animals of the control group Ⅱ,while the levels of IL-6,IL-10 and TNF-α were lower than those of the control group Ⅱ,also with significant difference(P ＜ 0.05 or P ＜ 0.01).The SOD level in the animals of the HBO group Ⅲ was higher than that in the animals of the control group Ⅲ,while the levels of MDA,IL-6,IL-10 and TNF-α were lower than those of the control group Ⅲ,also with significant difference(P ＜0.05).The IL-6 and TNF-α levels in the animals of the HBO group Ⅰ was lower than that in the animals of the HBO group Ⅱ,with significant difference (P ＜0.05).The SOD level in the animals of the HBO group Ⅰ was higher than that in the animals of the HBO group Ⅲ,while the levels of IL-6 and TNF-αα were lower,also with significant difference(P ＜0.05),and the levels of IL-10 and MDA were lower,with very significant difference(P ＜ 0.01).The SOD level in the animals of the HBO group Ⅱ was higher than that in the animals of the HBO group Ⅲ,while the levels of IL-6,IL-10,TNF-α and MDA were lower,with significant difference (P ＜ 0.05).Conclusions HBO pretreatment could improve poor hemodynamics of the animals induced by hypoxia,enhance antioxidant capacity of the body and increase ventricular function and hypoxia tolerance. Key words: Hyperbaric oxygen ; Acute hypoxia ; Hemodynamics ; TNF-α ; IL-10