| Cardiac hypertrophy is manifestations of pathology in hypertensive heart disease and an independent risk factor that leads to cardiovascular disease and increased mortality,but its development and evolution mechanism is not entirely clear.It is a compensatory response to provide normal stroke volume.The prevention and reversal of cardiac hypertrophy can significantly improve the prognosis of patients,therefore,further study of the mechanism of cardiac hypertrophy is very necessary.MAPK and PI3K-AKt mediated signaling pathways play a very important role in the formation of cardiac hypertrophy.Studying their expression will help to reveal the mechanism of cardiac hypertrophy and its reversal.Altered intracellular Na+ concentration([Na+]i)is a potentially important factor in the functional adaptation of the hypertrophied and failing heart?A rise in Na+ influx or an upregulation of Na+ influx transporters in the cardiac hypertrophy and heart failure models leads to increase [Na+]i.SCN5 A,the three isoforms of NKA and Na+–H+ exchanger 1(NHE-1)are all crucial intracellular sodium channel and transporters.Vinpocetine(Vinp)has a voltage-dependent sodium channel inhibitory effect.Vinpocetine inhibits sodium currents in rat cardiomyocytes,and its inhibitory effect on cardiomyocyte sodium currents is dose-dependent and voltage-dependent and reversible.Vinpocetine influence both the activation and inactivation processes of sodium channel,and resulted in attenuation of the slowly inactivating sodium currents.The inhibitory effect of vinpocetine on sodium channels in cardiomyocytes was significantly similar to that of tetrodotoxin(TTX).Studies have shown that tetrodotoxin can inhibit cardiac hypertrophy.Whether vinpocetine also has the effect of inhibiting cardiac hypertrophy remains to be further studied.There are few studies on influence and therapeutic effects of vinpocetine on the cardiovascular system,and these studies do not involve cardiac hypertrophy.In vitro and in vivo studies have shown that the use of isoproterenol(ISO)is a commonly used method of establishing a cardiac hypertrophy model.We will use myocardial cells and whole animal hypertrophy model induced by isoproterenol as the research object,use molecular biology,biochemistry,morphology and other technologies to investigate whether vinpocetine can inhibit the development of isoproterenol-induced cardiac hypertrophy by inhibiting the activation of MAPK and PI3K/Akt signaling pathways,as well as its influences on the expression of intracellular critical sodium channels and transporters and intracellular sodium concentration and to observe its effect on the whole animal hypertrophy model.Part ?:The effects of vinpocetine on ISO-induced hypertrophic cardiomyocytes of SD rats in vitroObjective: To observe the effect of vinpocetine on isoproterenol-induced hypertrophic cardiomyocytes in vitro;To investigate the regulatory role of phosphatidylinositol-3kinase(PI3K)and MAPKs signaling pathway;To detect the sodium ion concentration and the expression of key sodium channels and transporters in cardiomyocytes,and to explore its role in cardiac hypertrophy regulation.Methods: The effect of vinpocetine on cardiomyocyte activity was determine by MTT.After cultured for 72 hours,the cells which were treated with serum-free and phenol-free DMEM were divided into 6 groups:(1)control group: adding the same volume of serum-free DMEM medium as other groups;(2)ISO group: isoproterenol(10 ?mol/L);(3)Vinp1 group: ISO + Vinp(5 ?mol / L);(4)Vinp2 group: ISO + Vinp(10 ?mol/L);(5)Vinp3 group: ISO + Vinp(20 ?mol / L);(6)Vinp4 group: ISO+Vinp(40 ?mol/L).The cell surface area and the protein content of cardiomyocytes were measured after 48 hours of drug stimulation.The levels of ANP,BNP,PI3 K and AKt mRNA in cardiomyocytes were detected by RT-PCR after 6 hours of drug stimulation.The expression of the following proteins was detected by Western blotting: total Akt,phosphorylated Akt,total ERK,phosphorylated ERK,total JNK,phosphorylated JNK,total P38,phosphorylated P38,SCN5 A,NKA-?1,NKA-?2,NKA-?3 and NHE1.The concentration of sodium ions in cardiomyocytes carrying sodium-sensitive fluorescent dye CoroNa green was detected by confocal imaging.Results:(1)Vinpocetine concentration-dependent decreased the myocardial cell surface area and total protein content of hypertrophic cardiomyocytes,inhibited the expression of ANP and BNP mRNA in hypertrophic cardiomyocytes,improved the expression of PI3 K and AKt mRNA,increased the phosphorylation of AKt protein expression,and reduced phosphorylation of ERK,P38 protein expression.(2)Vinpocetine inhibited the increase in sodium concentration in ISO-induced hypertrophic cardiomyocytes.There was no significant change in the protein expression of SCN5 A in cardiomyocytes of ISO group and vinpocetine group(P>0.05).The protein expression of NKA-?2 and NKA-?3 was significantly decreased(both P<0.05),but NKA-?1 was not affected(P>0.05,ISO vs.control).Vinpocetine significantly attenuated ISO inhibition of NKA-?2 and NKA-?3 protein expression(P>0.05,Vinp vs.ISO).In contrast to the decrease in protein expression of NKA-?2 and NKA-?3,ISO resulted in a significant increase in the expression of NHE-1 protein,and the increase was not affected by vinpocetine.Conclusion: Vinpocetine has an inhibitory effect on ISO-induced cardiac hypertrophy.Its possible mechanism is to influence PI3K-AKt and MAPK signaling pathways and block sodium channels.Part ?: The effects of vinpocetine on the myocardial reconstruction of ISO-induced cardiac hypertrophy SD ratsObjective: To study the effect of vinpocetine on myocardial remodeling in ISO-induced hypertrophic SD rats.Methods: 55 adult male rats were randomly divided into four groups: 10 rats in the control group,45 rats in the model group which is established by inducing the cardiac hypertrophy with ISO.The rats with cardiac hypertrophy were further divided into three groups: 15 rats in the simple cardiac hypertrophy model group,15 rats in the cardiac hypertrophy with vinpocetine(10mg/kg /d)treatment group(Vinp I),the another 15 rats in the cardiac hypertrophy with vinpocetine(20 mg/kg/d)treatment group(Vinp II).All rats were kept under the same feeding conditions.Adult male SD rats were injected subcutaneously with 5 mg/kg isoproterenol twice a day(10am,8pm)for 4 weeks.The rats in the control group were given 2ml of saline twice in the same manner(10 am,8 pm)by subcutaneous injection.The rats in the control group and the cardiac hypertrophy group were given 2ml of saline by gavage daily.The rats in the Vinp?group and Vinp ? group were injected subcutaneously with 5 mg/kg/d isoproterenol twice a day(10 am,8 pm)and treated with vinpocetine 10 mg/kg/d and 20 mg/kg/d respectively.The main indicators observed after 4 weeks of treatment were the tail arterial blood pressure(instead of the mean arterial pressure as an index to measure the posterior cardiac load),the left ventricular mass index,the shortest diameter and cross-sectional area of the cardiac mast cells,the myocardial mass fraction,myocardial hydroxyproline content and other indicators of cardiac hypertrophy.Results: 1)Vinpocetine alleviated ISO-induced reduction of tail artery blood pressure in rats..Vinpocetine inhibited the left ventricular weight and left ventricular mass index(P<0.05)in ISO-induced simple cardiac hypertrophy,and the difference was significant.(2)Compared with the hypertrophy group,the shortest diameter of myocardial cells and the area of myocardial cells decreased in the vinpocetine group(P<0.05),and the difference was significant.(3)Compared with the hypertrophy group,the myocardial volume fraction and myocardial hydroxyproline content in the vinpocetine group were significantly decreased(P<0.05),and the difference was significant.Conclusion: Vinpocetine can effectively improve the blood pressure change,left ventricular mass index,myocardial interstitial collagen volume fraction and myocardial collagen content in ISO-induced SD rats,so as to improve myocardial remodeling and play the role of cardioprotection. |
PDF Full Text Request