The Study About Changes Of Metabolic Substances In The Blood And Urine During The Heat Acclimation Process

Thermal environment can be fallen into hygrothermal and dry-heat conditions.The regions,south of Yangtze River,are mostly in hygrothermal conditions.It's not abnormal that Summer temperatures are more than 35 ?,40 ? and even extreme high temperatures.The day and night temperature difference is small and the humidity is considerably high.The high humid environment seriously affect the human body heat,and in this environment people are engaged in the high intensity of physical activity with increased heat production and heat dissipation difficulties which are more likely to lead to increased body temperature,heat stress levels,thermal stress damage,heat stroke and even death.Severe high temperature and high intensity of physical activity is great challenge to our military operations.At present,the world take regard heat acclimatization as effective way to adapt to the thermal environment,improve the efficiency of the body work under thermal environment.Heat acclimation refers to that the body under the long-term thermal environment stimulation,appear a series of body improvement on the thermal environment adaptability,lower sensitivity to thermal environment of reaction.Heat acclimatization training methods include relying on long-term exposure to hot acclimatization and long-term effectively exercise with good physical fitness dealing with thermal environment,or the body in a hot environment combined with exercise can gain heat acclimatization in a relatively short time.Heat acclimatization training can improve soldiers' fighting capacity and it's significant to choose suitable soldiers for our army.The current evaluation methods of heat acclimatization effect embrace many physical indexes such as the core temperature,oral temperature,skin temperature rise,sweating rate and the change of heart rate.These indicators lack the sensitivity and specificity,and the volatility is bigger.It's not conducive to test them under our military work environment.As a result,it's urgent to look for highly sensitive and specific markers related to heat acclimation.Metabonomic is a kind of high throughput measurement technology which detect the body fluid composition and tissue with tiny changes,widely used in screening of molecular markers.This study first build rat model of heat acclimation testing rat plasma metabolic changes after the heat acclimation compared with rat which is without heat acclimation to screen molecular markers of heat acclimation;And then establish the model of the human body of heat acclimatization to detect metabolite changes of plasma and urineduring the heat acclimation process comparing the experimental and the control group before and after heat exercise stimulation.It's favorable to screen molecular markers of heat acclimatization.Part?Effect of heat acclimation on metabolites in rat plasmaObjective To observe the changes of plasma metabolites in rats after heat acclimation so as to screen the specific marker of heat acclimation.Methods A total of 20 SD rats were screened into 16 SD rats with considerable strength by exhaustive swimming with bearing heave stuff.16 SD rats were randomly divided into control and heat acclimation groups(n=8);Rats in heat acclimation group received 2 hour training a day and those in the control group received no training.After 14 days of heat acclimation,rat orbital blood was collected from control and heat acclimation groups.After a rest for 4 day,rats' arterial blood samples were collected under anesthesia after exercising in a thermal environment for 30 min in both groups.The changes of metabolites in plasmas from control and heat acclimation groups were examined by the nuclear magnetic resonance(NMR)using Bruker 600 MHZ,and the changes of plasmas metabolites were analyzed after heat acclimation and heat exercise stimulation in rats.Results In contrast to the control group,the heat acclimation group had significantly increased plasma unsaturated lipid,glutamate,lipid and dimethylamine(P<0.05),and significantly decreased glucose,myo-inositol,taurine,threonine and trimethylamine N-oxide(TMAO)(P<0.05);After heat exercise stimulation,the plasma TMAO,glutamate and lipid were observably decreased in heat acclimation group(P<0.05).Conclusion After heat acclimation and heat exercise stimulation,plasmas metabolites undergo great changes in rats.TMAO may serve as a marker of heat acclimation,which provide evidence for evaluation system for heat acclimation.Part ? Metabolite changes of the human body's plasma and urine for heat acclimationObjective To observe metabolite changes in human serums during heat acclimation process and filtrate the biomarker of heat acclimation.Methods 124 soldiers were stimulated with heat exercise and then their height,weight loss rate,oral temperature difference,heart rate difference and BMI were measured and calculated.According to these criterions,49 soldiers were eligible for this trial and then were randomly divided into the trial group(25 soldiers)and the control group(24 soldiers).The first 20 selected soldiers were attendees and the rest of soldiers were candidates.Soldiers in the trial group went through for 1-h heat acclimation training everyday lasting for 14 day;Soldiers in the control group did free activity for 1 h.After 4-day rest,all of soldiers in experimental group and control group were stimulated with exercise in the thermal condition.Soldiers' venous blood and urine were collected in1 st,7 st,14 st day,before and after heat exercise stimulation respectively and then were tested by nuclear magnetic resonance(NMR).Results Dimethylamine oxide in plasma,glutamic acid,unsaturated fatty acid,lactic acid content increased(P<0.05)and trimethylamine oxide,glucose,inositol,threonine,lipid content decreased in 1 st day of heat acclimation trial in contrast to in 7 st day(P<0.05);the content of unsaturated fatty acids and lipids in plasma increased(P<0.05),and the content of trimethylamine oxide,glucose,threonine,lactic acid decreased(P<0.05).before thermal environment movement with the stimulus,compared with the control group,the glutamic acid in plasma,lipids,lactic acid content increased,and the content of trimethylamine oxide and threonine decreased in the experimental group(P<0.05).After thermal environment movement stimulation,compared with the control group,the content of dimethylamine oxide was higher in plasma,and the content of glucose,threonine,trimethylamine oxide,glutamic acid,lactic acid and lipid reduced in the experimental group(P<0.05).However,metabolites of urine didn't change during heat acclimation process,before and after heat exercise stimulation(P>0.05).Conclusion During the heat acclimation trial process and after heat exercise stimulation(compared with the control group),TMAO and threonine in human plasma continued to decline and it may participate in the protection mechanism of heat acclimation towards human body.Thus,they can be used as a marker of heat acclimatization to provide strong clues for evaluating the heat acclimation and significant guidance for selections of excellent warriors in high temperature operation.