| AIM : The recent studies showed that there is a close relationship between the hypertension and cardiomyocyte apoptosis - But the abroad and domestic studies showed the different and paradoxical results .There is a number of genes that regulate the apoptotosis process, including Bcl-2 family in which bcl-2 inhibits apoptosis and bax induces apoptosis . The purpose of present study is to show cardiomyocyte apoptosis and the expression of bcl-2 and bax in the process of hypertension which is continuous and dynamic, without the limitation to the particular stages of hypertension . The structural and functional parameters of SD rats obtained by echocardiography with high frequency give not only clear stages of hypertension but also make correlation with the apoptosis and expression of apoptosis-associated genes .Methods: The renal hypertensive rat model was applied with two kidneys with one clip (2klc) .The sham operation was performed in control group .The experimental group was subdvivided into non-hypertrophic (NH group) ,concentric hypertrophic (CH group) and eccentric hypertrophic (EH group ) groups .according to the changes of blood pressure andechocardiographic parameters .The blood pressure was measured by the way of tail artery and carotid intubation .Left ventricular mass (LVM), relative wall thickmess (RWT), EF and FS were by echocardiography with high frequency probe. The cardiomyocyte apoptosis were detected by TUNEL method .The bcl-2 and bax proteins were detected by immunohistochemical technique.Results: The incidence of hypertension in the experimental group was 80% with mild atrophy of left kidney .There was no significant difference in LVM between control group and NH group , while a significant difference was found in LVM among the control group , CH group and EH group . LVPWd and IVSTd of CH group had significant thickness than Control group, NH group and EH group. LVEDd and LVESd in EH group are biggest among the all groups and thickness of wall of left ventricular .decrease. EF (%) and FS (%) decrease sharply in EH group . The cardiomyocyte apoptosis and the expression of bcl-2 and bax could be detected in every group. The cardiomyocyte apoptosis and the expression of bax gene protein is notably increased in EH group . The Bcl-2 gene protein expression remarkably increased in CH group . Echocardiography parameters such as LVPWd and IVSTd are negative with apoptosis and the expression of bax gene proteins in EH group . LVPWd IVSTd were positively related to the expression of bcl-2 gene proteins in CH . EF FS were inversely correlated with bax gene protein expression and were positive with bcl-2 gene protein expression . The cardiomyocyte apoptosis was found in inner layer of myocardium close toendocardium.Conclutions:1. The cardiac structure can be imaged clearly by echocardiography with high frequency probe and the structural and functional parameters can be obtained by 2-DE and M-mode echocardiography. Echocardiography canreflect accurately cardiac geometric alteration and functional change of hypertensive SD Rats .The wall thickness and size of left ventricular are sensible target.2. The cardiomyocyte apoptosis could be detected in every group and is notably increased in EH group which was found in inner layer of myocardium close to endocardium . There is the probability between the cardiomyocyte apoptosis and the development from concentric hypertension to eccentric hypertension.3. The expression of bcl-2 and bax could be detected in every group. The cardiomyocyte apoptosis and the expression of bax gene protein are notably increased in EH group . The Bcl-2 gene protein expression remarkably increased in CH group .The upregulation of bax gene protein expression may be associated with the increase of cardiomyocyte apoptosis in hypertensive rats, whereas upregulation of bcl-2 gene protein expression may be bound up with the decrease of cardiomyocyte apoptosis and cardiac hypertrophy.4. Echocardiography parameter LVPWd, IVSTd, EF and FS... |
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