Adaptive changes of rat′s right ventricle myocytes in myocardial remodeling

Objective:To investigate the changes and clinical significance of myocyte in right ventricle myocardial remodeling,a special technique connecting the arteria carotis communnis and venae jugularis externa was devel-oped,and an artificial shunt of left to right was made resulting in volume and pressure overload in rat models.Methods: There were four experimental groups and four control groups,and each had 10 weigh/sex matched Wistar rats.The experimental groups received the surgery mentioned above.After 1,2,4 and 8 weeks,the right ventricle pressure through the puncture of the right ventricle was measured directly.Histology and RT-PCR were used to examine the right ventricle remodeling and the changes of gene expression of β-myosin heavy chain,β-adrenergic receptors and bcl-2 in the right ventricle remodeling.Results: The right ventricle pressure elevated and maintained relatively stable at the 1st,2nd,4th and 8th week after surgery.No heart failure occurred in all groups.(1) There was increment of the ratio of right ventricle weight to the body weight(RV mg/BW g) after 4 weeks,and a statistical significance between the 8-week group and the control group(0.64±0.05 vs 0.43±0.03,P0.01);at the same time,the right ventricle/(left ventricle + septum) [R/(L+S)] ratio increased too((0.36±)0.04 vs 0.21±0.02,P0.05);(2) at the 4th week,the ratio of myocyte length to myocyte width and the myocyte cross-sectional area changed obviously.The ratio of myocyte length to myocyte width decreased [(7.1±0.3):1 vs(6.5±0.3):1,P0.05],meanwhile the myocyte cross-sectional area increased from 250.4?μm~2 to 328.8?μm~2(P0.05).At the 8th week,the changes still existed,but there was no statistical significance between the 4th and the 8th week;(3) the changes of gene expression of β-myosin heavy chain increased at the 1st week(1.37±0.21 vs 0.77±0.15,average of densitometry,P0.01) and the 2nd week(1.39±0.32 vs(0.79±)0.17 verage of densitometry,P0.01),and there was no significance between the 1st and the 2nd week.At the 4th and the 8th week,it returned to normal level;(4) the changes of gene expression of β-adrenergic receptors decreased at the 1st week(0.47±0.13 vs 0.80±(0.12,)P0.05,average of densitometry).At the 2nd,4th and 8th week,the changes still existed,but there was no difference among them and all of them had no difference from the 1st week;(5) the gene expression of bcl-2 elevated at the 1st and the 2nd week(the 1st week: 0.28±0.07 vs 0.16±0.03,P0.01;the 2nd week:(0.27±)0.07 vs 0.15±0.04,(P)0.01,average of densitometry).No changes occurred in the later 4 weeks.There was no difference between the 4th and the 8th week.Conclusion: Right ventricle overload could be developed by connecting the arteria carotis communnis and venae jugularis externa and induce myocardial remodeling.The gene expression of β-myosin heavy chain,β-adrenergic receptors and bcl-2 would be changed very soon according to the environment,which would do benefit for the heart function.The histological changes occur later,which is the result of early gene expression.