Objective By screening and passaging G0 generation Wistar rats,we obtained hypoxia-sensitive and hypoxia-tolerant G1 generation rats,and then the differences in hypoxia sensitivity among these rats were preliminarily explored.Methods 200 Wistar rats(half male and half female)were selected as G0 generation and placed in a controlled oxygen concentration system.The hypoxia tolerance time,which refers to the time from placement to near death,was recorded for the G0 generation rats at an oxygen volume fraction of 3％.30 rats(half male and half female)with the shortest hypoxia tolerance time were selected for mating and passage to obtain G1 generation hypoxia-sensitive rats.Similarly,30 rats(half male and half female)with the longest hypoxia tolerance time were selected for mating and passage to obtain G1 generation hypoxia-tolerant rats.An additional 24 standard Wistar rats were randomly divided into two groups:a control group and a model group,with 12 rats in each group(half male and half female).The control group was kept in a normoxic environment,while the model group,along with the G1 generation hypoxia-sensitive rats(G1 sensitive group)and G1 generation hypoxia-tolerant rats(G1 tolerant group),were placed in a hypobaric hypoxia chamber(simulating an altitude of 5 000 m).After 12 hours,various indicators,including blood gas,complete blood count,blood biochemistry,pathological sections,and hypoxia-related genes were detected or observed to compare the differences in hypoxia sensitivity among the 4 groups.Results Compared with the G0 generation standard rats,the hypoxia tolerance time of G1 generation rats was significantly prolonged(P＜0.01).Compared with the model group,the oxygen saturation(SatO2)in G1 tolerant group was significantly higher(P＜0.05).In the G1 sensitive group,the levels of white blood cell(WBC)count,neutrophil(NEUT)count,hemoglobin(HGB)concentration,hematocrit(HCT),red blood cell distribution width(RDW),platelet(PLT),and creatinine(Cr)significantly increased(P＜0.05 or P＜0.01),while actual bicarbonate(AB)content significantly decreased(P＜0.05),and the brain and lung coefficients were significantly elevated(P＜0.05).In addition,pathological section results showed that the brain and lung tissues in the model group,G1 sensitive group,and G1 tolerant group all suffered from significant damage,with no evident differences in the gene expression levels of hypoxia-inducible factor-1 α(HIF-1α)and vascular endothelial growth factor A(VEG FA)in brain tissues amongthe three groups(P＞0.05).Conclusion Compared with standard rats,G1 generation hypoxia-sensitive/tolerant rats exhibit good signs of hypoxia sensitivity/tolerance traits,but further screening and passage are still needed to purify them.

Objective A comparative study was conducted on rapid high-altitude models established in SD rats under two hypoxic stress modes,namely,a high-altitude field and simulated high-altitude environment,to evaluate the reliability of the simulated high-altitude test chamber.Methods SD rats were placed in a simulated rapid high-altitude animal experimental chamber(4000 m)or rapid high-altitude field laboratory(4010 m)to establish a rapid high-altitude rat model.After 24 or 72 h of exposure,physiological and pathological indicators related to high-altitude changes were collected and measured,mainly routine blood parameters,blood biochemistry,blood gas,oxidative damage indicators(superoxide dismutase(SOD),malondialdehyde(MDA),glutathione peroxidase(GSH-Px)),and inflammation indicators(interleukin 1β(IL-1 β),interferon-γ(IFN-γ),monocyte chemotactic protein 1(MCP-1)and interleukin 6(IL-6)),and pathological tissue analysis and hypoxia sensitive gene(hypoxia inducible factor-1α(Hif-1α)and vascular endothelial growth factor A(Vegfa))testing were performed.Finally,differential analysis was conducted on the result to obtain a differential evaluation report.Results At the same altitude,both high-altitude field and simulated high-altitude exposure for 72 h caused significant lung and brain damage.Under the same exposure time,the routine blood parameter,blood biochemistry,and blood gas result for the rats were similar.There were no significant differences in the detection of inflammation indicators(IL-6,IL-1β,MCP-1,and IFN-y),oxidative damage indicators(MDA,SOD,and GSH),or hypoxia-sensitive gene expression(Hif-1α and Vegfa)in the brain.However,partial pressure of carbon dioxide(PaCO2)and base excess(BE)were significantly higher in the simulated-72 h group than the other treatment group.The lung hypoxia-sensitive genes(Hif-1α and Vegfa)in the simulated-72 h group showed no significant expression difference with control group,and the brain coefficient of the high-altitude field treatment group was significantly higher than that of the simulated high-altitude treatment group.These result indicate that there may be slight differences between models prepared in high-altitude field and simulated high-altitude environments.Conclusions The simulated high-altitude animal experimental chamber can successfully establish a rapid high-altitude animal model.The simulated altitude can be appropriately increased on the basis of 4000 m.If an altitude of 4000 meters is used,the exposure time should be greater than 24 h but slightly shorter than 72 h.The simulated high-altitude experimental module has good reliability,but it is advisable to use plateaus for on-site experiments as much as possible,if conditions permit.