A Preliminary Study Of HIF-1 And INOS On Placetental Dysfunction After Cardiopulmonary Bypass

CHAPTER ?ESTABLISHMENT OF AN IN VITRO CIRCULATION MODEL OF FETALObjective To establish a cardiopulmonary bypass model of fetal sheep and observe the effect of this model on fetal sheep.Methods Pregnant sheep(pregnant 120-140 days)8,were randomly divided into control group and bypass group,each group 4.The control group was performed in lower median incision and then exposed the uterus,incised the uterus,exposed the fetus,incised one side upper limbs of the fetal and the trocar was inserted into the axillary artery to detect hemodynamics and collect blood samples.The fetus is opened in the middle of the chest,the main pulmonary artery and right atrium were inserted into the arterial cannula and venous drainage tube and connected to the extracorporeal circulation pipeline and the reservoir.Finally,a cardiopulmonary bypass was established using a centrifugal pump and a placenta(as a sole oxygenator).The control group was not bypassed and observed for 3 h.The operation of the bypass group and the establishment of cardiopulmonary bypass were the same as those in the control group.The bypassgroup was bypassed for 60 min and observed after shutdown for 2 h.The mean arterial pressure,heart rate and axillary artery blood gas outcome were measured before bypass,30 min after bypass,60 min after bypass,1 h after the end of the bypass,and 2 h after the end of the bypass.Results Throughout the experiment,all pregnant sheep and fetal sheep were survived.The blood pressure and heart rate of the pregnant sheep are stable.However,the mean arterial pressure,heart rate,and arterial blood gas values of the fetal sheep were all changed before and after cardiopulmonary bypass.The mean value of mean arterial pressure(MAP)and heart rate(HR)of the fetus increased first and then decreased,and the overall trend of arterial oxygen pressure(Pa O2)decreased,but there was no statistical significance(P> 0.05).The changes in blood p H of the fetus arteries were significant during cardiopulmonary bypass,and the change was statistically significant(F = 6.081,P = 0.049).The PH decreased gradually with time,after 1 hours of stopping,the PH reached the lowest valley and then increased(P<0.01),in the control group and the bypass group,the decrease amplitude of the PH was different,and the decrease rate of the bypass group was large(P=0.005).The carbon dioxide partial pressure(Pa CO2)increased significantly in fetal sheep during cardiopulmonary bypass(F=9.951,P=0.004).The Pa CO2 increased gradually with time,after 1 hours of stopping,the Pa CO2 reached the peak and then dropped(P<0.01),in the control group and the bypass group,the decrease amplitude of the Pa CO2 was different,and the increase rate of the bypass group was large(P<0.01).The changes in blood Lactate of the fetus arteries were significant during cardiopulmonary bypass,and the change was statistically significant(F=24.580,P=0.003).The Lactate increased gradually with time,after 1 hours of stopping,the Lactate reached the peak and then tend to be stable(P<0.01),in the control group and the bypass group,the decrease amplitude of the Lactate was different,and the increase rate of the bypass group was large(P=0.002).Conclusions The effect of cardiopulmonary bypass on fetal sheep is obvious.There was an irreversible acidosis,hypoxia and hypercapnia,high lactate,fetal heart rate and mean arterial pressure in the fetal sheep after cardiopulmonary bypass.We hypothesized that this may be related to placental dysfunction after cardiopulmonary bypass.This animal model can provide some experimental basis for the clinical application of fetal cardiopulmonary bypass.CHAPTER ?STUDY ON THE EXPRESSION AND CORRELATION OF HIF-1? AND INOS IN PLACENTA OF FETAL SHEEP DURING CARDIOPULMONARY BYPASSObjective To detect the expression of HIF-1? and i NOS in the placenta of the fetus before and after cardiopulmonary bypass and to explore their role in the mechanism of placental dysfunction after cardiopulmonary bypass.Methods The placental tissue of the placenta was extracted approximately1x1x1cm3 in the control group and the bypass group before and after the cardiopulmonary bypass.Semi-quantitative analysis of HIF-1?m RNA and i NOS m RNA transcription by fluorescence RT-PCR.The expression levels of HIF-1?and i NOS in placenta were detected by immunohistochemistry(IHC)and the expression of HIF-1? and i NOS in placental tissue was analyzed by Image-Pro Plus6.O(IPP)color image analysis system.Results The expression of HIF-1?m RNA and i NOS m RNA was detected in placental tissue after cardiopulmonary bypass.HIF-1?m RNA RT-PCR semi-quantitative results found that the bypass group compared with the control group was p <0.05(t = 4.642 p = 0.001),the comparison between the groups was t = 9.013 p <0.01,the difference was statistically significant.i NOSm RNA RT-PCR semi-quantitative results found that the bypass group compared with the control group was p<0.01(t=13.47 p<0.01),the comparison between the groups was t=24.85 p<0.01,the difference was statistically significant.The expression of HIF-1? and i NOS were positive in placental tissue after cardiopulmonary bypass.HIF-1? was mainly expressed in placental tissue of the co-trophoblast cells and cytoplasmic cytoplasm,i NOS was mainly expressed in placental placental tissue of the vascular endothelial cell membrane.Theexpression levels of HIF-1? in the placenta were 0.166 ± 0.021 0.350 ± 0.055,there was significant difference between the two groups before and after cardiopulmonary bypass p <0.05(t = 3.019 p = 0.019),the comparison between the groups was p<0.05(t=3.334 p=0.013),the difference was statistically significant.The expression levels of i NOS in the placenta were 0.169±0.0310.373±0.043,there was significant difference between the two groups before and after cardiopulmonary bypass p<0.05(t=3.317 p=0.013),the comparison between the groups was p<0.05(t=3.090 p=0.018),the difference was statistically significant.Conclusions The expression of HIF-1? and i NOS in the placenta of fetal sheep after cardiopulmonary bypass may be involved in the physiological process of placental dysfunction after fetal cardiopulmonary bypass.We hypothesized Both may form a HIF-1? / i NOS signaling pathway that mediates fetal placental dysfunction during cardiopulmonary bypass.