Metabolomics Study Of Mild Hypothermia On Myocardial Protection In Rats After Cardiac Arrest

Objective:The purpose of this study was to use ultra-high performance liquid chromatography-time-of-flight mass spectrometry(UPLC-QTOF-MS)technology to find biomarkers for mild hypothermia to protect the rat myocardium after cardiac arrest(CA),and to preliminary explore possible metabolic pathways.Provide new ideas for the application of further clinical practice.Methods:1.The CA model was prepared by asphyxiation.30 SD rats were divided into 3 groups according to the random number table method:Norm(normal temperature)group(n=10),Hypo(moderate hypothermia)group(n=10),and sham operation(Sham)Group(n=10),the Sham group did not suffocate,only anesthesia,tracheal intubation and vascular puncture.The Norm group slowly rewarmed after ROSC to maintain the rectal temperature at(37.0±0.5)℃,the Hypo group ROSC quickly within20 minutes Induce hypothermia,maintain rectal temperature at(33.0±0.5)°C,and maintain it for 3h,slowly rewarm to(37.0±0.5)°C after3 h,rewarming rate 0.5°C/h;record the asphyxia before CA in rats of Norm group and Hypo group Duration,duration of cardiopulmonary resuscitation(CPR)to spontaneous circulation recovery(ROSC),0min,10 min,30min,60 min after ROSC,mean arterial pressure(MAP),heartrate(HR)when mechanical ventilation stops At 24 h after surgery,rats in Norm group and Hypo group were sacrificed at 24 h after ROSC.Myocardial tissue samples were collected for pathological and metabolomics detection.Another 30 rats were randomly divided into three groups: Norm group(n=12),Hypo group(n=13),Sham group(n=5),and the survival rate of the three groups of rats on the 7th day after operation was recorded.2.Using UPLC-QTOF-MS technology to conduct metabolic analysis on three groups of rat myocardial tissue samples,import the preprocessed data into SIMCA-P 14.1 software,and after quality control and normalization processing,the obtained data was subjected to principal component analysis(PCA).Partial least squares discriminant analysis(PLS-DA),PLS-DA produces variable importance projection values(VIP),identify potential biomarkers through VIP>1.0 and P<0.05,and introduce endogenous differential metabolites MetaboAnalyst 4.0software for metabolic pathway analysis.Results:1.The weight,rectal temperature,mean arterial pressure,and heart rate of the three groups of rats were not statistically different from the baseline level(all P>0.05).The hemodynamic indicators of the normal temperature group and the mild hypothermia group under the basic state,asphyxia before CA There was no statistically significant difference induration and duration of CPR to ROSC(all P>0.05).The asphyxia CA model was successfully prepared and homogenized.2.The results of the 7th day survival rate of rats showed that the 7th day survival rate of rats in mild hypothermia group was higher than that of normal temperature group,but there was no statistical difference(P>0.05);The degree is lighter than the normal temperature group.3.Compared with the sham operation group,the normal temperature group identified 32 differential metabolites,mainly related to cysteine and methionine metabolism,purine metabolism,glycerophospholipid metabolism,glycerolipid metabolism,and steroid hormone metabolism pathways;By comparison,20 different metabolites were identified,mainly related to purine metabolism and valine/leucine/isoleucine metabolism pathways.Conclusion:1.SD rats were used to construct asphyxia CA model.The results of myocardial histopathology and survival analysis showed that mild hypothermia can alleviate myocardial injury after CA to a certain extent.2.This study used UPLC-QTOF-MS technology and found that the potential biomarkers for mild hypothermia to protect the myocardium after CA are 5’-methylthioadenosine,L-cysteine,xanthine,hypoxanthine,Adenosine monophosphate,glycerol 3-phosphate,gamma linolenic acid,thromboxane B2,palmitic acid,methylmalonic acid.3.This study confirmed from the analysis of metabolic pathways that mild hypothermia may play a protective role by reducing oxidative stress,reducing cardiomyocyte apoptosis,improving coagulation dysfunction,and improving the energy metabolism of myocardial tissue after ischemia-reperfusion.