ABSTRACT
Objective To evaluate the effect of resuscitation with hypertonic sodium chloride hydroxyethyl starch 40 injection (HSH40) mixed with suberoylanilide hydroxamic acid (SAHA) on oxidative stress responses of lung tissues and histone acetylation in a rat model of lethal hemorrhagic shock after entering high altitude for the first time.Methods Forty-five healthy male Wistar rats,aged 3-4 months,weighing 250-300 g,were transported from the breeding area at altitude 1500 m to the experimental area at altitude 3 780 m.The rats were divided into 3 groups (n=15 each) using a random number table:sham operation group (group Sham),hemorrhagic shock group (group HS),and resuscitation with HSH40 mixed with SAHA group (group HSH/SAHA).Lethal hemorrhagic shock was induced by removing 40％ of blood volume from the left femoral artery at a constant speed within 10 min,followed by removing 15％ of blood volume from the right femoral vein at a constant speed within 50 min.Only cannulation was performed,and the rats received no blood letting or resuscitation in group Sham.The animals were resuscitated via the right femoral artery after successful establishment of the model,SAHA 7.5/Kg dissolved in HSH40 4 ml/kg was infused within 5 min in group HSH+SAHA.Immediately before blood letting,immediately after blood letting and at 3 h after resuscitation (at the time of death for the rats survived less than 3 h),arterial blood samples were obtained for blood gas analysis,and pH value,partial pressure of arterial carbon dioxide (PaCO2),partial pressure of arterial oxygen (PaO2) and arterial oxygen saturation (SaO2) were recorded.The rats were sacrificed after blood samples were collected from the abdominal aorta at 3 h after resuscitation (at the time of death for the rats died within 3 h after resuscitation),and lungs were removed for examination of the pathologic changes which were scored (with a light microscope) and for determination of wet to dry weight ratio (W/D ratio),activity of superoxide dismutase (SOD) and content of malondialdehyde (MDA) and expression of histone H3 acetylation at lysine 9 (Ac-H3K9) in lung tissues (by Western blot).Results Compared with group Sham,the lung injury score,W/D ratio and content of MDA were significantly increased,and the activity of SOD was decreased in HS and HSH+SAHA groups,pH value and PaCO2 were significantly decreased and PaO2 and SaO2 were increased immediately after blood letting and at 3 h after resuscitation in group HS,and PaO2 and SaO2 were significantly increased immediately after blood letting and at 3 h after resuscitation,pH value and PaCO2 were decreased immediately after blood letting,and the expression of Ac-H3K9 was up-regulated in group HSH+SAHA (P＜0.05).Compared with group HS,pH value,PaCO2,PaO2 and SaO2 were significantly increased at 3 h after resuscitation,the lung injury score,W/D ratio and content of MDA were decreased,the activity of SOD was increased,and the expression of Ac-H3K9 was up-regulated in group HSH+SAHA (P＜0.05).Conclusion The mechanism by which resuscitation with HSH40 mixed with SAHA exerts lung protection may be related to inhibiting oxidative stress responses and histone acetylation in lung tissues in a rat model of lethal hemorrhagic shock after entering high altitude for the first time.
ABSTRACT
Objective To evaluate the effect of suberoylanilide hydroxamic acid (SAHA) on liver injury induced by lethal hemorrhagic shock in rats first entering high altitude.Methods Forty healthy male SpragueDawley rats,aged 2-3 months,weighing 240-280 g,transported from breeding grounds at an altitude of 1520 meters to the experimental station at an altitude of 3780 meters,were randomly divided into 4 groups (n =10each):sham operation group (group S),lethal hemorrhagic shock group (group LHS),normal saline group (group NS),and SAHA group.Anesthesia was induced with inhalation of 3% isoflurane and maintained with inhalation of 0.5%-1.0% isoflurane.Lethal hemorrhagic shock was induced by withdrawing blood from the femoral artery in groups LHS,NS and SAHA.Normal saline 0.25 ml and SAHA 7.5 mg/kg (0.25 ml) were injected intravenously over 2 min after completion of blood-letting in groups NS and SAHA,respectively.The survival rates with 3 h were recorded.Blood samples from femoral veins were taken before blood-letting,immediately after completion of blood-letting and at 3 h after completion of blood-letting (immediately after death if the survival time was less than 3 h) for determination of serum aspartate aminotransferase (AST),alanine aminotransferase (ALT) and lactic dehydrogenase (LDH) activities by the colorimetric method.Liver specimens were taken at 3 h after completion of blood-letting or immediately after death for examination of the pathological changes of the liver and for determination of c-Jun N-terminal kinase (JNK),phosphorylated-JNK (p-JNK) and caspase-3 expression and acetylation of H3K9 in liver tissues by Western blot.Results Compared with group S,the activities of serum AST,ALT and LDH were significantly increased in the other three groups (P ＜ 0.01).Compared with LHS and NS groups,the activities of serum AST,ALT and LDH were significantly decreased,the survival rate within 3 h and acetylation of H3K9 were increased,caspase-3 expression was down-regulated,and p-JNK/JNK ratio was decreased in group SAHA (P ＜ 0.05 or 0.01).The pathological changes of the liver were severe in LHS and NS groups and attenuated in SAHA group.Conclusion Administration of SAHA in early shock can significantly protect the liver after lethal hemorrhage in rats first entering high altitude,and increased acetylation of H3K9 and inhibition of the JNK/caspase-3 apoptotic pathway in liver tissues are involved in the mechanism.