心肌肥厚的PTEN负性调控与卡托普利干预对其影响的实验研究

目的检测异丙肾上腺素(isoproterenol,ISO)诱导的心肌肥厚大鼠PTEN mRNA、蛋白水平表达及卡托普利(captopril,Cap)对其表达的影响,从而探讨PTEN的负性调控在心肌肥厚中的作用。方法24只大鼠随机分为对照组、ISO组、Cap+ISO组。利用小剂量ISO持续背部皮下注射大鼠,建立心肌肥厚模型。在观察期末,分别测定各组大鼠体重、心脏湿重、左室湿重,计算出心脏重量/体重及左室重量/体重;电镜观察超微结构的变化,并测定左室收缩末压、左室舒张末压、左心室压力上升及下降最大速率等指标。RT-PCR测定心肌组织PTEN mRNA,Western blot测定其蛋白表达。结果(1)与对照组比较,ISO组、Cap+ISO组的左室重量/体重、心脏重量/体重、左室收缩末压、左室舒张末压均升高(P≤0.05),左室压力上升及下降最大速率(±dp/dtmax)均下降(P≤0.05)。(2)与ISO组相比,Cap+ISO组的左室重量/体重、心脏重量/体重、左室收缩末压、左室舒张末压均下降(P≤0.05,P≤0.01),左室压力上升及下降最大速率(±dp/dtmax)均升高(P≤0.05,P≤0.01)。(3)与对照组比较,ISO组、Cap+ISO组的PTEN mRNA、蛋白表达均增加。(4)与ISO组比较,Cap+ISO组的PTEN mRNA、蛋白表达增加。结论ISO诱导心肌肥厚PTENmRNA、蛋白表达升高,心肌肥厚过程中存在负性调控,PTEN是一种内源性抑制心肌肥厚的重要因子。卡托普利不仅能明显抑制心肌肥厚,改善血液动力学参数,而且还能上调心肌PTEN水平,这是其抑制心肌肥厚的又一机制。

PTEN negatively regulates isoproterenol-induced cardiac hypertrophy and effects of captopril on PTEN expression

OBJECTIVE: To examine the negative regulation role of PTEN in isoproterenol-induced cardiac hypertrophy by testing the expression of PTEN mRNA and protein and to explore the effects of captopril (Cap) on PTEN expression. METHODS: Twenty four rats were randomly divided into three groups: control group, ISO group, and ISO+Cap group. The following parameters were examined:body weight (BW), heart weight (HW), left ventricular weight (LVW), left ventricular end-diastolic pressure (LVEDP), left ventricular end-systolic pressure (LVESP) and +/- dp/dt(max). The ratio of HW/BW and LVW/BW was calculated. PTEN mRNA and protein were tested by RT-PCR and Western blot, respectively. RESULTS: (1) Compared with the control group, the ratio of HW/BW and LVW/BW, LVEDP and LVESP were all increased in ISO group and ISO+Cap group (P < 0.05), but +/- dp/dt(max) was decreased (P < 0.05); (2) compared with the ISO group, the ratio of HW/BW and LVW/BW, LVEDP, LVESP were all decreased in ISO+Cap group (P < 0.05), but +/- dp/dt(max) was increased (P < 0.05); (3) compared with the control group, PTEN mRNA and protein were up-regulated in ISO group and ISO+Cap group; (4) compared with the ISO group, PTEN mRNA and protein were up-regulated in ISO+Cap group. CONCLUSIONS: PTEN mRNA and protein are up-regulated in isoproterenol-induced cardiac hypertrophy. Captopril can up-regulate PTEN expression in cardiac hypertrophy. There is a negative regulative mechanism in cardiac hypertrophy process, in which PTEN is probably an endogenous negative regulator of cardiac hypertrophy.