Expression Chang Of P93 MRNA In Process Of Rats Pressure-overload Cardiac Hypertrophy

Objective: Cardiac hypertrophy is one of important compensation mechanism for heart failure. It's important characteristic is cardiac myocytes hypertrophy,the change of stroma component ( also named ventricular remodeling),the decrease of compliance and pump function of heart. When cardiac hypertrophy happens, the phenotype of contraction protein change together with stroma rebuilding. These changes as two important dangerous factor will lead to the decrease of myocardial contractility. So the morbidity of heart failure must be decreased significantly if we can find a pathway which can improve myocardial contractility.p93 is a cardiac-specific kinase, It's molecular weight is 93KD. p93 can directly interact with cardiac troponinⅠand actin. Therefore, we speculate that p93 may be involved in the regulation of contraction protein by an unknown signaling pathway and then regulate cardiac contractility,participate in the development of cardiac hypertrophy.The energy which cardiac contraction need mainly come from mitochondrial oxidative phosphorylation together with ROS production.PrxIII is the P93-interacting protein. It's function is to eliminate the excess ROS in mitochondrion and protect cell against oxidative stress. So when the load of cardiac muscle change, the contractility of cardiac muscle and the expression of interacting protein may also change. Many studies showed that the expression of PrxIII in ventricular remodeling after myocardial infarction were increased. But the expression change of PrxIII, the relationship between PrxIII and p93 in cardiac hypertrophy is unclear.The aim of our work is to investigate the expression change of PrxIII and p93 in process of rats over-load cariac hypertrophy, to find the relationship between their expression level and the change of morphology and function of cardiac myocytes, to lay a foundation for the function study of p93.Methods1 Animals and preparation of cardiac hypertrophy models Male SD rat weighting 190-200g were divided randomly into shame operation control group(Con) and Model group(Mod). Con and Mod group were again divided into 24 hour(_24H),two weeks(_2W),four weeks(_4W),six weeks(_6W) groups, respectively. Cardiac hypertrophy models were made through partial ligation of abdominal aorta as described by Anversa P. Con group only underwent operating procedure without ligating abdominal aorta.2 SBP,DBP,LVSP,LVEDP,±dp?dt_max assay Rats were anaesthetized with chloral hydrate (5ml/kg), right carotid artery was separated and a cardiac catheter connected with BL-420E+ TAI MENG media mix sigal analysis system was inserted into right carotid artery and left ventricle cavity. The SBP,DBP,LVSP,LVEDP,±dp/dt_max were recorded.3 HMI assayThe rat hearts were cut and cleaned with iced physiological saline. Then, the weight of heart were recorded. The ratio of heart weight (HW) and body weight (BW) namely HMI were caculated.4 Morphological change of the left ventricleThe left ventricle sample was fixed with 4% paraformaldehy. embedded in paraffin, cranked out 5 micron thick common section, HE stained, then observed by light microscope.5 The ultrastructure chang of left ventricle sampleThe left ventricle sample was fixed with the mixture of 3% paraformaldehy and 1% glutaraldehyde. Then, the ultrastructure chang of left ventricle samples were observed with electron microscope.6 The expression of p93 and Prx III mRNA in interventricular septumThe interventricular septum sample was immediately submerged in liquid nitrogen and stored at -70℃. The total RNA were extracted with Trizol, The relative mRNA content were measured by RT-PCR using GAPDH as inner standard.Results1 Blood pressure (BP) SBP and DBP in Con_24H were 12.13±0.69, 9.47±0.98, respectively; those in Mod_24H were 12.51±1.37, 10.04±1.01, respectively, which were not higher than those in Con_24H(P>0.05); The SBP(14.55±1.04) and DBP(12.03±2.08) in Mod_2W were significantly higher than SBP(12.33±0.52) and DBP (8.99±0.94) in Con2w(P<0.05): The SBP(16.26±2.41) and DBP(12.10±1.61) in Mod_4W were significantly higher than SBP(12.40±0.74) and DBP (9.32±0.78) in Con4w(P<0.01); The SBP(16.04±2.32) and DBP(13.40±1.94) in Mod_6W were also significantly higher than SBP(12.71±1.35) and DBP (9.41±1.08) in Con_6W(P<0.01).2 Function of contraction and diastole of left ventricle Compared to LVSP(12.37±0.74),LVEDP (0.66±0.07),﹢dp?dt_max(424±72) and -dp?dt_max (406±58) in Con_24H, the LVSP (12.58±1.01),LVEDP(0.71±0.10),﹢dp?dt_max(431±69) and -dp?dt_max (419±63) in Mod_24H were not changed(P>0.05). The LVSP(15.01±1.95),﹢dp?dt_max(491±85) and -dp?dt_max (486±78) in Mod_2W were higher than LVSP (12.56±1.13),﹢dp?dt_max(416±77) and -dp?dt_max (411±64) in Con_2W (P<0.05). but, The LVEDP (0.69±0.11) in Mod_2W were not higher than the LVEDP(0.68±0.09) in Con_2W(P>0.05).The LVSP(16.47±2.16) in Mod_4W were significantly higher than those (12.55±1.06) in Con_4W(P<0.01). but LVEDP (0.81±0.08),﹢dp?dt_max(421±80) and -dp?dt_max (404±57) in Mod_4W were not significantly higher than LVEDP(0.70±0.08),﹢dp?dt_max(407±81) and -dp?dt_max (398±66) in Con_4W(P>0.05). The LVSP (16.16±1.54) and LVEDP (1.83±0.10) in Mod_6W were significantly higher than LVSP(12.77±1.87) and LVEDP (0.75±0.09) in Con_6W ( P<0.01). But﹢dp/dt_max(340±66) and -dp/dt_max (338±52) in Mod_6W were lower than﹢dp/dt_max (421±76) and -dp/dt_max (410±65) in Con_6W(P<0.05).3 HMIThe HMI in Con_24H were 3.11±0.23,The HMI in Mod_24H were 3.15±0.19, there were no statistical difference between Con_24H and Con_2W, the HMI(3.43±0.16) in Mod_2W were also not higher than HMI (3.07±0.49) in Con_2W(P>0.05); but the HMI(3.95±0.30) in Mod_4W were higher than HMI(3.10±0.37) in Con_4W(P<0.05), the HMI (4.35±0.74) in Mod_6W were also higher than HMI (2.94±0.27) in Con_6W(P<0.05).4 The morphology change of left ventricle under light microscopeIn all control groups, myocardial fiber arrage tidily, nucleus clear. These was no change between Con_24H and Mod_24H. Compared to control groups, the myocardial fiber of Mod2w,Mod4w and Mod6w become broader gradually, the interval between myocardial fiber also become wider, blood capillary proliferate in stroma.5 The ultrastructure chang of left ventricle under electron microscopeIn all control groups, myocardial fiber arrange tidily, light band,dark band and Z line clear, structure of mitochondrion is normal. These is no change between Con_24H and Mod_24H. In Mod2w,Mod4w and Mod6w, sarcomere clear, mitochondrion increase and accumulate ( especially evident for Mod4w and Mod6w), the mitochondrial crista become thicker significanty. in addition, we also can see a number of electron-dense secreted particle in intracellular especially surrounding of mitochondrion.6 The expression of p93 mRNA in interventricular septum Compared to Con_24H (0.49±0.06) and Con_4W (0.51±0.08) respectively, the expression of p93 mRNA in Mod_24H (0.47±0.07) and Mod_4W(0.54±0.09) were not changed. (P>0.05). The expression of p93 mRNA in Mod_2W (0.23±0.04) were significantly lower than that in Con_2W (0.50±0.07) (P<0.01), but the expression of p93 mRNA in Mod_6W (1.12±0.16) were much higher than that in Con_6W (0.41±0.07) (P<0.01).7 The expression of Prx III. mRNA in interventricular septum The expression of PrxIII mRNA in Mod_24H (0.29±0.07) were lower than that in Con_24H (0.65±0.10) (P<0.05). The expression of Prx III mRNA in Mod_2W (0.20±0.04) and Mod_4W (0.34±0.02) were much lower than that in Con_2W (0.63±0.13) and Con_4W (0.61±0.08), respectirely (P<0.01). But the expression of Prx III mRNA in Mod_6W (0.91±0.16) were much higher than that in Con_6W (0.60±0.09) (P<0.05).Conclusion1 Cardiac hypertrophy model can be made successfully through partial ligation of rat abdominal aorta with size-7 needle.2 Change of hemodynamics and HIM are related with the degree of cardiac hypertrophy and myocardium function. 3 With the occurrence and development of cardiac hypertrophy, the sarcomere of cadiocyte extend gradually, mitochondrion increase and crista become denser.4 With the development of cardiac hypertrophy, the express of p93 and PrxIII enhanced gradually. This suggest that p93 and PrxIII are involved in the process of over-load cardiac hypertrophy, but the mechanism is unknown.