基于钠钾ATP酶对津液“收敛固涩”作用探讨五味子“生熟异用”作用机制

Due to insufficient knowledge on the concept of astriction, the scientific significance for the different use of crude and processed Schisandra chinensis in disease therapy remains largely unknown. By analogy analysis, we found that Na,K-ATPase in luminal epithelium cells plays a critical role in the production, distribution, and excretion of body fluid. Based on this notion, we presume that the therapeutic effect of Schisandra chinensis is closely relevant to Na,K-ATPase activity. To test this hypothesis, we examined the effects of the crude, wine-processed and vinegar-processed Schisandra chinensis on hypoxia-induced acute lung injury and spleen diarrhea model, as a result, the crude Schisandra chinensis prevented hypoxia-induced acute lung injury by specifically counteracting the downregulated Na,K-ATPase activity in lung epithelium, however, the vinegar-processed Schisandra chinensis inhibited diarrhea by specifically counteracting the downregulated Na,K-ATPase activity in intestine epithelium. Because different subtypes of protein kinase C are involved in the downregulation of Na,K-ATPase in the lung and intestine epithelium, we hypothesize that chemical constituents that have selective inhibitory effects on PKC subunits are present in the crude and vinegar-processed Schisandra chinensis, additionally, both ginseng in “ShenMiao San” and Tetradium ruticarpum in “SiSheng Wan”can amplify the selective effects of the crude and vinegar-processed Schisandra chinensis by increasing the ATP-producing activity of mitochondria. The results of this study will elucidate the mechanism for the different use of crude and processed Schisandra chinensis, highlight the importance of Chinese prescription in understanding the use of Schisandra chinensis, enrich our knowledge on the pathological mechanism for body fluid missing, and ensure the proper use of Chinese medicine in clinic.

“生熟异用”是五味子用药特色，但科学内涵未有共识，其原因之一在于缺乏对 “收敛固涩”作用的合适表征。我们发现腔上皮细胞膜钠钾ATP酶在机体津液生成、宣发肃降与排泄中发挥类似于“收敛固涩”的关键作用，由此推测五味子的作用与钠钾ATP酶活性密切相关。为验证该推测，分别考察生、酒、醋五味子对缺氧急性肺损伤与脾虚腹泻模型的影响，发现生五味子重在刺激肺上皮钠钾ATP酶活性抗肺损伤，而醋五味子长于激活肠上皮钠钾ATP酶活性止泻。有趣的是，不同蛋白激酶C（PKC）亚型分别介导肺、肠上皮钠钾ATP酶活性抑制，由此推测生、醋五味子中存在对PKC不同亚型具有选择性抑制的活性成分；此外，生脉散中人参与四神丸中吴茱萸能通过增强线粒体功能，放大生、醋五味子对肺、肠作用的选择性。本研究将揭示五味子“生熟异用”科学内涵，彰显复方在理解五味子“生熟异用”的重要性，丰富现代医学对津液滑脱的认识，指导临床合理用药。

收敛固涩药是一类在中医临床上应用广泛，治疗“津液耗散滑脱”等病症的重要药物。作为“收敛固涩”代表药物，五味子性酸、甘、温，归肺、心、肾经，具有收敛固涩、益气生津、补肾宁心等功效，临床常用于久嗽虚喘、遗尿尿频、久泻不止、自汗、盗汗等。但现代药理学研究表明五味子及其他收敛固涩药的活性大都集中在抗癌、降血脂、保肝等方面，与传统主治功能存在明显差异。产生该差异的主要原因在于缺少对“收敛固涩”、“津液耗散滑脱”这些传统中医药理论的科学表征、准确认识与合适的研究模型。基于钠钾ATP酶所介导的腔层上皮细胞对水分与营养物质的吸收特征，本研究发现该系统与中医“津液”学说有很高的相似性，由此提出钠钾ATP酶介导的腔层上皮细胞吸收系统可能是收敛固涩中药发挥作用的关键机制这一科学假说。. 为验证该假说，本研究首先建立基于的钠钾ATP酶定量方法，该方法较经典的放射性同位素示踪法及常规比色法具有安全性、高灵敏性与稳定性等优势。采用该定量方法，发现收敛固涩药能特异性激活肺、肠上皮细胞钠钾ATP酶活性，并促进细胞对水分与萄萄糖的吸收，而非收敛固涩药无此作用。同时发现生、醋五味子均能显著激活肠上皮细胞钠钾ATP酶活性，并保护肠上皮细胞钠钾ATP酶功能受抑。进一步研究发现五味子木脂素类成分具有保护肺、肠上皮细胞钠钾ATP酶功能。线粒体是给钠钾ATP酶供能的主要细胞器。基于鱼藤酮诱导的线粒体损伤模型，本研究发现五味子木脂素类成分能显著抑制线粒体功能受损状态下膜电位MMP的降低与活性氧ROS的升高，且部分五味子木脂素成分能抑制正常状态下细胞中ROS的生成。因此，保护线粒体功能，为上皮细胞膜钠钾ATP酶提供足够能量，可能是五味子为代表在内的收敛固涩类中药发挥固涩作用的共性与重要生物学机制。. 本研究揭示了五味子及其他收敛固涩药的新作用机制，为临床合理使用该类药物提供了新的理论依据。