The Effects Of Intrauterine Chronic Hypoxia On ENOS Expression And Phosphorylation Of Cardiomyocytes Of Adult Male Rats

ObjectiveChronic hypoxia in utero will lead to limited fetal growth,which can lead to cardiovascular disease in adulthood.by building the rat model of intrauterine chronic hypoxia,study its effects on the cardiomyocyte morphology,myocardial collagen fiber deposition,eNOS(endothelial nitric oxide synthase)expression and eNOS phosphorylation level of adult male rats,and probe into the possible mechanisms of intrauterine chronic hypoxia resulting in cardiovascular diseases of adult offspring.MethodTake 12 healthy SD pregnant rats,and randomly divide them into two groups on the seventh day of pregnancy,namely,hypoxia group(group H)and control group(group C).Place the hypoxia group in the low-oxygen cabin in the every day(8 hours),and control the oxygen concentration in low-oxygen cabin at(10.0±0.5)%.Place the control group in the low-oxygen cabin too,but inject air and maintain the oxygen concentration same as that of atmosphere outside.Repeat the process above until maternal rat delivery(21st day of pregnancy).After maternal rat delivery,select 6 offspring male rats from each group with the random number table,and normally feed them to 11 months of age.Observe and measure the myocardial fiber dimension of rats with hematoxylin-eosin staining method(HE);observe and measure the collagen fiber area ratio with Mason staining method;detect the myocardial cell eNOS mRNA expression of offspring rats with Real Time PCR method;detect the eNOS,eNOS Ser1177(serine 1177 loci)expression,and eNOS Thr495(threonine 495 loci)expression of offspring rats' myocardial cells with Western Blot method.Results(1)Intrauterine chronic hypoxia will not change the diameter of male rats' cardiomyocytes(F=0.785,P>0.785),or change the collagen fiber area ratio of myocardial tissues(F=0.23,P>0.23);(2)Intrauterine chronic hypoxia can cause the reduction in the eNOS mRNA expression of male rats' cardiomyocytes(F=1.280,P<0.001);(3)Intrauterine chronic hypoxia can cause the eNOS protein expression level of male rats' cardiomyocytes decreased(F=1.003,P<0.001),the eNOS Ser1177 phosphorylation level decreased(F=0.425,P<0.425),and eNOS Thr495 phosphorylation level increased(F=0.324,P<0.001).Conclusions(1)Intrauterine chronic hypoxia will neither affect the diameter male rats' cardiomyocytes,nor cause myocardial fibrosis;(2)Intrauterine chronic hypoxia can significantly lower the eNOS transcription of male rats' cardiomyocytes,as well as the expression of post-transcriptional level;(3)Intrauterine chronic hypoxia can increase eNOS Thr495 expression,but decrease eNOS Ser1177 expression,and the Ser1177/Thr 495 imbalance will significantly reduce the activity of eNOS.