| Objective To observe abnormal heart rate of fetal rats by creating a model of hyperhomocysteinemia(Hhe)in pregnant S-D rats, and to investigate the relationship among homocysteine(Hcy),mRNA expression of Connexin43(Cx43), Folic Acid(FA)and CHD.Methods The Hhe model of pregnant Sprague-Dawley rats was set up through intraperitoneal injection of Hcy and 40 pregnant rats were randomly assigned to 4 groups,which were low dose group of l%Hcy(Group-A),high dose group of 2%Hcy(Group-B),interention group of FA(FA+2%Hcy,Group-C) and control group of Normal Saline(Group-D).Each group had 10 pregnant rats. These rats in Group-A, Group-B and Group-C were injected intraperitoneally with Hcy on the seventh day of pregnancy, the dosage of which was as follows:1%Hcy 100mg/Kg, 2%Hcy 200mg/Kg and 2%Hcy 200mg/Kg. Rats in Group-C were administrated to FA following 4mg/Kg which was dissolve in water.The rats in Group-D were injected intraperitoneally with same amount of saline. Hysterotomy was performed on the twentieth day of pregnancy.The hearts of fetal rats of each group were observed by stereoscope.The levels of Hcy in plasma of pregnant rats were detected before pregnancy and on the twentieth of pregnancy with High performance liquid chromatography- electrochemistry method (HPLC-EC) .RNA extraction was performed from hearts in a part of fetal rats of each group.mRNA expression of Cx43 in hearts of these fetal rats of each group were demonstrated by Real-time quantitative PCR.Results1. By comparing the levels of Hcy in plasma of pregnant rats in Group-A and Group-B before pregnancy (11.94±0. 39μmol/L, 11.81±0.88μmol/L) and on the twentieth of pregnancy (20.90±1.08μmol/L,30.47±1.1μmol/L), we calculated p<0.01 and found Hcy > 15μmol/L on the twentieth of pregnancy. This prompted that Hhe model of pregnant rats was set up successfully. Through the comparison of the levels of Hcy in 4 groups on the twentieth of pregnancy,the results were as follows: Group-B(11.81±0.88μmol/L) > Group-A(20.90±1.08μmol/L) > Group-D (10.98±0.77μmol/L), Group-B(30.47±1.11μmol/L) >Group-C (21.92±1.23μmol/L) > Group-D (10.98±0.77μmol/L),p<0.01.2. There was a difference among the abnormal heart incidence of fetal rats,which were 9.57%,14.13%,9.73% and 0.75% respectively.A comparison of incidence in Group-B &Group-A or Group-B&Group-C,we calculated p>0.05.The abnormal heart rate of fetal rats Group-D was significantly lower than that of Group-A,Group-B and Group-C respectively, p< 0.01.3. mRNA expression of Cx43 in hearts of fetal rats in 4 groups were different. By comparing the expression levels in fetal rats with CHD and without CHD including in the same groups and in the different groups, we calculated p<0.01. A comparison of the expression levels in Group-B & Group-A or Group-B & Group-C,the result was p<0.01. There was no deference among fetal rats without CHD in 4 groups. The levels of Hcy in plasma of pregnant rats was correlated with mRNA expression of Cx43 in in hearts of fetal rats positively. The up-regulation of Cx43mRNA may cause cardiovascular abnormalty of fetal rats.Conclusion1. The mRNA expression of Cx43 in fetal rats with CHD is higher than that of normal heart,and Hcy may cause cardiovascular abnormalty of fetal rats by up-regulation of Cx43mRNA.2. Folic Acid may low the level of Hcy in blood plasma of pregnant rats.
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