| Myspalax cansus(Rodentia,Myospalacinae,Myspalax)which lives on the loess plateau of our country.This unique underground rats life-long living under the cave,it developed many mechanism to adapt its special circumstances at all levels.In this study,we used Gansu zokor and SD rats (Sprague-Dawley)for the object,acute hypoxia stimulation,analysis and comparison of indicators of changes in heart function,blood serum of catechol Amine hormone levels change and the expression of HIF-1αand Fos in the medulla of two animals.Trying to find the different hypoxia tolerance mechanisms between wild rats and mice,research shows that:1.Compared with normoxia group,the Gansu zokor's various indicators of heart function had no significant change(P>0.05) in the different terms of acute hypoxia,in addition to HR and + dp / dtmax showed slightly downward trend,MAP,mCASP,LVSP,-dp/dtmax showed an upward trend,but compared with the control group,all indicators remained at a constant level.Compared with normoxia group,the weight of ventricular had no significant change,the weight of the right ventricle and the proportion of left and right maintained at a constant level of basic,left ventricular mass had slight fluctuations,but with the control group not significantly different(P>0.05).Compared with normoxia group,the SD rats' various indicators of heart function had significant change(P>0.05) in the different terms of acute hypoxia,showed the trend of start up and terminal decline,which MAP,mCASP,LVSP showed upward trend in hypoxia 0.5-4h and then decline,HR,+ dp / dtmax,-dp/dtmax showed upward trend in hypoxia 0.5-2h and then decline.Last dead in the 6.5-7h stage of acute hypoxia.Compared with SD rats,in addition to MAP,+dp / dtmax slightly low,the Gansu zokor's various indicators of heart function had significantly low(P<0.01).Its + dp / dtmax had no significant difference(P>0.05)to SD rats in hypoxia 0.5 and 1h,all other indicators of heart function were significantly lower than the SD Rats(P <0.01)at the same terms of acute hypoxia.The weight of left and right ventricular had no significant difference(P>0.05)between hypoxia and normoxia group in SD rats.Compared with the the Gansu zokor at the same status left and right ventricular weight significantly different(P<0.05),but the proportion of right and left ventricle in different states had no significant difference(P>0.05)brtween them.The results show that Gansu zokor adapt to the hypoxia environment,which can survive under hypoxic conditions wiht the stability heart function.2.Compared with normoxia group,the Gansu zokor's catecholamine levels in serum showed up trend in the different terms of acute hypoxia,in addition to have significant differences(P>0.05)between normoxia and acute hypoxia 8h group,there were no significant difference in the other group(P>0.05).Although the Gansu zokor's norepinephrine also showed up trend,compared with normoxia group there were no significant difference(P>0.05).Compared with SD rats,the Gansu zokor's catecholamine and norepinephrine levels showed the same trend of upward at the initial stage of acute hypoxia(0.5-4h),in addition to have significant difference(P<0.05) between their catecholamine levels in normoxia,there were no significant difference(P>0.05)among other terms of acute hypoxia between Gansu zokor and SD rats.SD rats'catecholamine and norepinephrine levels in serum levels showed sharp decline in the 6h stage of acute hypoxia and dead in the 6.5-7h stage.However,these two hormone in Gansu zokor's serum showed the trend of up along with the hypoxia-term increase.The results show that the levels of hormone in Gansu zokor has good adaptation to hypoxia.3.Fos were expressed extensive in the medulla of Gansu zokor under the all conditiongs.Leveis of Fos began to increase gradually from the treatment of acute hypoxia 0.5 h,respectively,to 1.47 times(0.5h),1.52 times(1h),1.93 Times(2h),2.39 times(4h) and 2.81 times(6h), 5.38 times(8h) that of normoxia group.Compared with normoxia group,in addition to have no significant difference(P>0.05)in hypoxia 0.5 h and have significant differences(P<0.05)in hypoxia 1 h,there were very significant difference(P< 0.01)in other groups.HIF-1αwere expressed abroad in the medulla of Gansu zokor under normoxia.Levels of HIF-1αbegan to increase gradually from the treatment of acute hypoxia 0.5 h,respectively,1.53 times(0.5h),1.72 times(1h),2.01 Times(2h),2.27 times(4h) and 2.76 times(6h),4.92 times(8h) that of normoxia group.Compared with normoxia group,in addition to have significant difference (P<0.05)in hypoxia 0.5 h,there were very significant difference(P< 0.01)in other groups.Fos were expressed extensive in the medulla of and SD rats under normoxia and the levels of expression were significant higher(P<0.05) than SD rats'.The of Fos began to increase from the treatment of acute hypoxia 0.5 h.Respectively,compared with SD rats,the levels of Fos expression had no significant difference(P>0.05) in hypoxia 0.5,1,2 and 4h.But SD rats' Fos were very higher and 1.85 times that of in hypoxia 6 h.SD rats dead in the stage of hypoxia 6.5-7h,but Gansu zokors' Fos expression also showed upward.HIF-1αwere expressed abroad in the medulla of Gansu zokor under normoxia and was 4.16 times that of SD rats'.Levels of HIF-1αbegan to increase gradually from the treatment of acute hypoxia 0.5 h and to keep the way of continued growth along with the hypoxia-term increase.The expression of SD rats' HIF-1αat the highest level after acute hypoxia 2h,then began to gradually decrease followed by hypoxia 4 and 6 h.Compared with SD rats,except in hypoxia 0.5,1 and 2h there were no significant difference(P>0.05),levels of HIF-1αwere significantly higher than the SD rats (P<0.01) and respectively,to 2.36 and 3.69 times that of SD rats at the stage of 4 and 6 h.The highest expression of HIF-1αin Gansu zokors' at the stage of hypoxia 8h,but SD rats dead at the stage of acute hypoxia 6.5 -7h.The results show that Gansu zokor will smooth launch its central level of hypoxia adaptation mechanism in hypoxic conditions.In conclusion,acute hypoxia stimulate effects on heart function,catecholamine hormones in serum and the expression of HIF-1αand Fos are all different in zokors and rats.Compared with normoxia group,the Gansu zokor's had no significant change in the different terms of acute hypoxia.SD rats'various indicators of heart function reached to demonstrated disordered and failure in some terms of acute hypoxia and dead in hypoxic stress 6.5-7h.SD rats'catecholamine and norepinephrine levels in serum levels showed sharp decline in the 6h stage of acute hypoxia and dead in the 6.5-7h stage.However,these two hormone in Gansu zokor's serum showed the trend of up along with the hypoxia-term increase.HIF-1αwere expressed abroad in the medulla of Gansu zokor under normoxia,Accompanied by a sustained high level of Fos expression,the expression of showed upward along with the time of hypoxia increase,levels of HIF-1αwere higher than SD rats in variety hypoxia stimulation.Because Gansu zokor long-term living in the underground environment of hypoxia,and not sensitive to the hypoxia environment.In the stimulation of hypoxia,Gansu zokor may smooth launch of its own mechanism to hypoxia from molecular,cellular level to the overall coordination,and not to appeared heart failure.Gansu zokor will remain survival at the hypoxic conditions with the stability in cardiac function. |
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