地高辛通过上调RGS2表达以减缓AngⅡ诱导小鼠高血压性心肌肥厚发生发展的研究

目的通过观察地高辛(Digoxin)干预血管紧张素Ⅱ(AngⅡ)诱导的ApoE-/-小鼠高血压性心肌肥厚模型后,对G蛋白调节因子2(regulator of G protein signaling 2,RGS2)的影响,探讨地高辛治疗高血压性心肌肥厚的作用与可能的机制。方法 30只雄性ApoE-/-小鼠随机分为对照组、AngⅡ模型组和AngⅡ+Digoxin治疗组。所有小鼠从术前1d至术后处死前均接受0.5%二甲基亚砜或地高辛溶液腹腔注射治疗,并且在术后28d获取心脏组织,通过组织学检查、苏木精-伊红(HE)染色切片分析技术评定心肌组织形态学变化、RGS2的mRNA及蛋白表达水平来评价地高辛的作用。结果与AngⅡ模型组相比,AngⅡ+Digoxin组全心重量、左心室壁厚度、心肌细胞直径均明显减少(P<0.05或P<0.01),RGS2mRNA变化不明显,而蛋白表达增高(P<0.01),心肌肥厚明显减轻。同时检测小鼠在术前3d,手术当天,术后3、7、14、28d的血压,发现AngⅡ+Digoxin组与AngⅡ模型组比较,术后7d和14d血压下降(均P<0.05),术后28d则差异无统计学意义。结论地高辛可能通过上调ApoE-/-小鼠高血压心肌肥厚模型RGS2的表达,有效减轻心肌肥厚,这说明地高辛可能在抑制心肌细胞肥大中起重要作用。

Angiotensin Ⅱ induced upregulation of Gαq/11,phospholipase Cβ_3 and extracellular signal-regulated kinase 1/2 via angiotensin Ⅱtype 1 receptor

Background The role of the Gαq/11-mediated signal transduction pathway in angiotensin Ⅱ (Ang Ⅱ) induced cardiac hypertrophy remains unclear. This study was to investigate the role of the Gαq/11 signal transduction pathway in the development of cardiac hypertrophy in 2K1C hypertensive rats and in cultured neonatal rat ventricular myocytes (NRVMs) and to elucidate the effects of the pathway on Ang Ⅱ induced cardiac hypertrophy. Methods Renal hypertension was induced in 2K1C hypertensive rats by placing a silver clip around the left renal artery. At 8 weeks after operation,the systolic blood pressure,the ratio of left ventricular weight to body weight (LV/BW),and the concentration of AngⅡ in the heart were measured. The protein levels of Gαq/11 and extracellular signal-regulated kinase 1/2 (ERK1/2) were assayed by Western blot analysis,and the activity of phospholipase C (PLC) in the myocardium was detected using [ 3H]-PIP_2 as a substrate. Changes in [ 3H]-leucine incorporation and in the protein levels of the signal molecules Gαq/11,PLCβ_3,and ERK1/2 were measured after NRVMs were stimulated with 10 -7 mol/L AngⅡ. Results The protein levels of Gαq/11 and ERK1/2 in the hearts of 2K1C rats increased by 35.8% and 31.9%,respectively,compared with the sham group. The PLC activity in the 2K1C group was also significantly increased ( P <0.05). The levels of Gαq/11,PLCβ_3,and ERK1/2 increased significantly after NRVMs were stimulated by AngⅡ. The upregulation of Gαq/11,PLCβ_3 and ERK1/2 in NRVMs occurred prior to [ 3H]-leucine incorporation increases,and could be inhibited with losartan. Conclusion AngⅡ can initiate cardiac hypertrophy and upregulate signal molecules in the Gαq/11-mediated signal transduction pathway,such as Gαq/11,PLCβ_3 and ERK1/2,at both tissue and cellular levels.

缬沙坦对自发性高血压大鼠左心室肥厚心肌细胞GRK2的表达及亚细胞分布的影响

目的观察缬沙坦对自发性高血压大鼠(SHR)左心室心肌细胞G蛋白偶联受体激酶2(GRK2)的表达及亚细胞分布的影响。方法 18只SHR随机分为对照组(n=6),低剂量缬沙坦组[SHR_L组,10mg/(kg·d),n=6]和高剂量缬沙坦组[SHRH组,30mg/(kg·d),n=6],由6月龄喂养至8月龄,处死后分离心脏,通过免疫荧光标记、激光共聚焦显微镜及Werstern blot方法,观察左心室心肌细胞GRK2的表达及亚细胞分布的变化。结果与对照组比较,SHR_L组及SHR_H组左心室心肌组织总蛋白、浆蛋白及膜蛋白GRK2表达水平有明显减少(P<0.05),SHRH组较SHR_L组减少更明显(P<0.05);与对照组比较,SHR_L组及SHR_H组GRK2在心肌细胞膜上分布减少,SHR_H组较SHR_L组进一步减少。结论缬沙坦能减少SHR左心室心肌细胞GRK2的表达及在细胞膜上的分布,这可能是逆转心肌肥大及心室重塑的机制之一。

比索洛尔对高血压左室肥大大鼠心肌细胞GRK2表达的影响

目的观察比索洛尔对大鼠肥大心肌细胞G蛋白受体激酶2(GRK2)的影响,探讨比索洛尔改善心肌重塑的可能机制。方法以自发性高血压心力衰竭大鼠(SHR)为研究对象,通过免疫荧光标记、共聚焦显微镜及Werstern Blot等方法,检测比索洛尔干预后SHR左心室心肌细胞中GRK2的表达及其分布。结果心肌总蛋白中GRK2表达6月龄SHR组和WKY组比较无明显变化(60.7±1.9,62.1±2.2,P>0.05),8月龄SHR比6月龄SHR显著增加(78.5±2.1,60.7±1.9,P<0.05),均有心肌细胞膜上的聚积,8月龄SHR药物组比非药物组显著减少(65.9±2.2,78.5±2.1,P<0.05),心肌细胞膜上聚积减少。结论在心肌肥大的过程中,GRK2表达增加且有心肌细胞膜(闰盘)上的聚积,说明GRK2与心肌肥大关系密切,参与心肌肥大细胞信号途径的调控;比索洛尔抑制心肌细胞GRK2的表达以及细胞膜上的聚积,提示改善心肌肥大细胞信号途径的调控可能是比索洛尔逆转心脏重塑的机制之一。

Regulation of angiotensin Ⅱ on Gαq/11 protein of vascular smooth muscle cell and its underlying mechanism

To study the regulation of angiotensin Ⅱ (Ang Ⅱ) on Gαq/11 protein of vascular smooth muscle cell (VSMC) and its underlying mechanism, the protein synthesis was detected by [3H]-leucine incorporation. Gαq/11 expression was measured by Western blot in cultured VSMC of rat aorta. The results showed that the level of Gαq/11 was down-regulated after stimulated by Ang Ⅱ for 1-6 h, while it was upregulated significantly by 12-24 h stimulation (P 【 0.01) in VSMC. The [3H]-leucine incorporation of VSMC was increased after 24 h Ang Ⅱ stimulation. The biphase regulation of Ang Ⅱ on Gαq/11 protein was blocked by the Ang Ⅱ type I receptor (AT1) specific antagnist losartan or PLC inhibitor U73122, while PD98059 did not have this effect. These data indicated that Ang Ⅱ contributed to VSMC hypertrophy by regulating the level of Gαq/11, and this effect was mediated mainly through AT1 receptor-PLC signal transduction pathway.

钙调神经磷酸酶依赖的信号通路在大鼠心肌肥大中的作用

目的：观察钙调神经磷酸酶（ｃａｌｃｉｎｅｕｒｉｎ，ＣａＮ）依赖的信号通路在大鼠心肌肥大中的作用。方法：通过腹主动脉缩窄复制大鼠压力超荷性心肌肥大模型，观察ＣａＮ特异性抑制剂环孢素Ａ（ｃｙｃｌｏｓｐｏｒｉｎ Ａ，ＣｓＡ）对大鼠心系数以及血浆及心肌组织心钠素（ａｒｉｔｒｉａｌｎａｔｒｉｕｒｅｔｉｃ ｐｅｐｔｉｄｅ，ＡＮＰ）水平的影响。同时，在培养的大鼠心肌细胞及心脏成纤维细胞上，观察ＣｓＡ 对血管紧张素Ⅱ（ａｎｇｉｏｔｅｎｓｉｎ Ⅱ， ＡｎｇⅡ） 刺激的３Ｈ亮氨酸及３Ｈ胸腺嘧啶参入的影响。结果：腹主动脉缩窄大鼠心系数较假手术组增高３８％ （ Ｐ＜ ０．０１） 。应用ＣｓＡ 治疗的大鼠心系数下降了８５％ （ Ｐ＜０ ．００１）。同时，观察到腹主动脉缩窄大鼠心肌组织及血浆ＡＮＰ含量较对照组分别增高１３５ ％ 和１１７ ％ （Ｐ＜ ０ ．０１） ，ＣｓＡ 处理后，ＡＮＰ分别下降了１６ ％ 和１４％ 。在培养的大鼠心肌细胞及心脏成纤维细胞上，观察到ＣｓＡ（０ ．１ ～１０μｍｏｌ·Ｌ－１）可以浓度依赖的方式抑制血管紧张素Ⅱ刺激的３Ｈ亮氨酸及３Ｈ胸腺嘧啶参入的增加。结论：ＣａＮ 依赖的信号通路可能参与了压力超负荷及血管紧张素Ⅱ诱导的大鼠心?

川穹嗪对大鼠心肌肥大JAK-STAT通路作用

目的了解川穹嗪对大鼠心肌肥大JAK—STAT通路的影响。方法建立心肌肥大动物模型，40只大鼠随机分为4组，每组10只，分别为血管紧张素Ⅱ（AngⅡ）组（给予AngⅡ36mg·kg^-1·d^-1）、AngⅡ加川穹嗪组（给予AngⅡ36mg·kg^-1·d^-1，川穹嗪50mg·kg^-1·d^-1）、AngⅡ加PBS组（给予AngⅡ36mg·kg^-1·d^-1，PBS50mg·kg^-1·d^-1）、对照组（给予生理盐水36mg·kg^-1·d^-1），计算心肌肥大指数。培养、鉴定新生大鼠心肌细胞，每天分别给予AngⅡ1×10^-7mol／L（AngⅡ2组）、AngⅡ1×10^-7mol／L＋川穹嗪1×10^-4mol／L（AngⅡ加川穹嗪2组），以不加药物作为对照2组，培养7d，应用RT—PCR方法检测各组大鼠心肌细胞心房利钠肽（ANP）相对水平，Western—blot检测心肌肥大信号转导途径分子pJAK2、pJAK1、pSTAT3表达。结果AngⅡ组与对照组比较，心肌肥大指数明显增高，差异有统计学意义（F=32．675，q=6．25，P〈0．01），AngⅡ＋川穹嗪组与AngⅡ组相比较，心肌肥大指数明显下降，差异有显著意义（q=5．19，P〈0．05）。AngⅡ2组与对照2组比较，ANP mRNA表达增加，差异有显著性（F=45．674，q=11．23，P〈0．01）；AngⅡ＋川穹嗪2组与AngⅡ2组比较，ANP mRNA表达减少，差异有显著性（q=7．53，P〈0．01）。AngⅡ2组加入川穹嗪前后pJAK1、pJAK2、pSTAT蛋白表达量比较，差异有显著性（F=24．456～36．549，q=8．02～10．25，P〈0．05、0．01）。结论川穹嗪能通过干扰心肌肥大JAK—STAT信号转导通路抑制心肌肥大。

美托洛尔抑制原发性高血压左室肥大心肌细胞中G蛋白受体激酶2的表达

背景持续的高血压并发心肌肥大,目前对心肌肥大的机制尚未完全明确,围绕细胞信号转导通路的研究已成为热点;对于心肌肥大的干预治疗,β受体阻滞剂显示出了确切的效果,但其改善心肌重塑的机制尚未明了。目的观察美托洛尔对肥大心肌细胞中G蛋白受体激酶2(GRK2)的影响,探讨美托洛尔改善心肌重塑的可能机制。方法以自发性高血压大鼠(SHR,n=6)为研究对象,通过免疫荧光标记、荧光显微镜及Werstern Blot等方法,检测美托洛尔干预后SHR左心室心肌细胞中GRK2的表达及其分布。WKY大鼠(n=6)为对照组。结果心肌总蛋白中GRK2表达6月龄SHR组和WKY组比较无明显变化(GRK2,6月龄SHR:59.5±1.6比6月龄WKY60.9±2.0,n=6,P>0.05),8月龄SHR比6月龄SHR显著增加(GRK2,8月龄SHR:74.7±1.3比6月龄SHR:59.5±1.6,n=6,P<0.01),均有心肌细胞膜上的聚积,8月龄SHR药物组比非药物组显著减少(GRK2,8月龄SHR药物组:64.7±1.5比8月龄SHR:74.7±1.3,n=6,P<0.01),心肌细胞膜上聚积减少。结论在心肌肥大的过程中,GRK2表达增加并且有心肌细胞膜(闰盘)上的聚积,提示GRK2与心肌肥大有关系,参与心肌肥大细胞信号途径的调控。抑制心肌细胞GRK的表达以及细胞膜上的聚积可能是美托洛尔改善心脏重塑的机制之一。