Objective:Heme chloride(Hemin)is an in vitro purified form of natural heme and an important raw material for anti-anemia and antitumor drugs.This study aims to analyze the protective effect of Hemin on tissue damage in low-pressure oxygen chamber simulated plateau hypoxic mice,and explore its role in anti-plateau hypoxia. Methods:Thirty male BALB/c mice were randomly divided into a blank group,a positive drug group(acetazolomide,200 mg/kg),a Hemin low-dose group(15 mg/kg),a Hemin medium-dose group(30 mg/kg),and a Hemin high-dose group(60 mg/kg)with intraperitoneal injection.The anti-hypoxic activity of Hemin was explored by atmospheric closed hypoxia experiment and the optimal dose was screened.Thirty-six male BALB/c mice were randomly divided into a blank group,a hypoxia group,a positive drug group,and a Hemin high-dose group.The plasma inflammatory factor levels and oxidative stress indicators malondialdehyde(MDA),glutataione(GSH),and superoxide dismutase(SOD)levels of myocardium,brain,lung,and liver tissues were measured in different groups with hypoxia for 24 h.The degree of histopathological damage of mice was observed with HE staining.The degree of protection of Hemin against tissue hypoxia injury was detected with the hypoxia probe piperidazole. Results:Compared with the blank group,the survival time of mice in the positive drug group,the Hemin medium-dose group,and high-dose group was significantly extended(all P<0.05),with the highest prolongation rate in the Hemin high-dose group.Compared with the hypoxia group,mice in the Hemin high-dose group showed a significant increase in SOD level and GSH content of brain tissue,and a significant decrease in MDA content of lung tissue(all P<0.05).The results of HE staining and hypoxia probe showed that Hemin had a significant protective effect on the damage of liver,heart,brain and lung tissues of mice with hypoxia,and the most obvious effect on that of the brain tissue. Conclusion:Hemin has an effect of improvement on oxidative stress and inflammatory response caused by hypoxia,and has obvious protective effect on tissue damage caused by hypoxia.

Red blood cells(RBCs)are the primary mediators of oxygen transport in the human body,and their function is mainly achieved through conformational changes of hemoglobin(Hb).Hb is a tetramer composed of four subunits,with HbA being the predominant Hb in healthy adults,existing in two forms:tense state(T state)and relaxed state(R state).Endogenous regulators of Hb conformation include 2,3-diphosphoglyceric acid,carbon dioxide,protons,and chloride ions,while exogenous regulators include inositol hexaphosphate,inositol tripyrophosphate,benzabate,urea derivative L35,and vanillin,each with different mechanisms of action.The application of Hb conformational regulators provides new insights into the study of hypoxia oxygen supply issues and the treatment of sickle cell disease.