针刺改善自发性高血压大鼠心肌肥厚及舒缩功能损害的机制研究

Cardiac plasticity, characterized as myocardial hypertrophy, could be induced by long-lasting hypertention. Myocardial hypertrophy actually includes several phathological alterations such as myocyte hypertrophy, non-myocyte hyperplasia of and interstitial fibrosis, which may be accompanied with functional impairment of left ventricle. There are no any therapies of western medicine which could completely delay or stop the progress from hypertension to myocardial hypertrophy even to cardiac diastolic or systolic malfunction. Searching for new therapies to stop or delay the progress is currently the focus for medical study. Acupuncture was showed to excite parasympathetic nervous system and produce antihypertensive and cardioprotective effects, suggesting a possibility for acupuncture to inhibit the hypertensive myocardial hypertrophy and cardiac malfunction. Spontaneous hypertensive rats will be used in the proposed study as the animal model to determine if or not the Renin-angiotensin II-aldosterone system, β1-adrenoceptor, related growth factors and cytokines is/are involved in the mediation of the acupuncture-produced inhibition of myocyte's hypertrophy and myocardial fibrosis, by means of the techniques including Small Animal Ultrasound(Vevo 770) for detection of cardiac function in small animals, Myocyte Calcium and Contractility Recording System (Ionoptix) for simultaneous recording of intracellular calcium transient and contraction in single ventricular myocyte and Western Blotting etc.. The special attention will be pay to analyze the roles played by the intracellular calcium and its signaling components in mediating the attenuation of acupuncture on the hypertension-induced impairment of cardiac function, in particular the left ventricular diastolic malfunction which occurred usually earlier than the systolic malfunction. There is so far few study involved in the same topic as aforementioned, suggesting the clinical significance of the study proposed above.

长期高血压可导致以心肌肥厚为重要特征的心室重塑，心肌肥厚的病理主要表现为心肌细胞肥大、非心肌细胞增生和间质纤维化，同时可伴有左心室功能损害。迄今现代医学尚无办法完全阻滞高血压心肌肥厚（细胞肥大和心肌组织纤维化）及心衰的发展进程，寻找新的有效阻滞该进程的方法乃是医学界的研究热点。已知针灸可兴奋迷走神经、治疗高血压、改善心脏功能，为针灸抑制高血压心室肥厚及心脏功能损害提供了可能。 本项目拟以自发性高血压大鼠为研究对象，采用小动物B超、单个心肌细胞收缩与细胞内钙同步记录及分子生物学等技术，探讨与心肌肥厚和心功能受损密切相关的血管紧张素II系统、β1－肾上腺素受体、生长因子及细胞因子等在介导针刺抑制心肌肥大、心肌组织纤维化中的作用；并重点分析心肌细胞钙及其信号调节因子在介导针刺抑制高血压心功能损害、尤其是早期左室舒张功能损害中的作用。此方面的研究几乎未见报道，应具有较积极的临床启示意义。

长期高血压可以引起心脏结构的异常及高血压性心肌舒缩功能的损害。近年来，逆转左心室肥厚、心肌纤维化及左心室舒缩功能损害被认为是治疗慢性高血压的关键环节。本研究以12周龄自发性高血压大鼠（SHR）作为研究对象，采用无创血压记录和超声心动图技术，观察连续8周电针“内关”穴对SHR血压和心脏结构、功能的影响；在确定电针有效改善高血压-心肌肥厚/纤维化-心功能损害病理进程的基础上，通过免疫组织化学染色、Western Blotting、Real-Time PCR等方法，揭示电针“内关”穴发挥该效应的分子生物学机制，并重点分析了心肌细胞内钙信号调节因子在介导针刺抑制高血压心功能损害中的作用。实验结果表明：SHR除表现为血压升高外，其左心室壁厚度、HW/BW、LVWI显著增加，射血功能明显减弱，CVF及Hyp、collagen I、collagen III的表达异常增高，说明出现心肌肥厚为主要特征的心肌重塑，并伴有心功能受损。电针内关穴可以显著地抑制SHR血压的升高，改善上述心肌肥厚、纤维化指标的异常，提示电针改善SHR高血压心肌肥厚发展进程疗效明确。电针内关穴在改善高血压-心肌肥厚的同时，可以明显抑制SHR血清或心肌组织中ACE、β1-AR、AT1R、TNF-α、TGF-β1、CTGF、MMP-9的异常表达；另一方面，电针内关穴抑制了SHR心肌组织中β1-AR、RyR2 蛋白表达的异常升高，明显增加了SHR心肌组织中SEACA2α的蛋白表达。同时电针内关穴减低了SHR单个左室心肌细胞对β1-AR激动剂作用下引起钙瞬变、收缩性能反应性的异常增强。增加了RyR2激动剂、SEACA2α抑制剂作用下引起钙瞬变、收缩性能反应性的异常降低。综上表明：电针内关穴可以有效地改善高血压大鼠心肌肥厚/心肌纤维化发展进程。血管紧张素系统、β1-AR及上述相关细胞因子（TNF-α）、生长因子（CTGF、TGF-β1）和酶类（MMP9）可能参与了电针抑制SHR高血压-心肌肥大/纤维化的作用机制；另一方面，β1-AR、SEACA2α、RyR2均可能参与介导了电针缓解高血压大鼠心肌舒缩功能损害的作用。