血小板通过炎症反应在盐敏感性高血压中的作用机制研究

The study on the mechanism of platelet in the development of salt-sensitive hypertension via inflammation

目的探讨血小板在高盐诱导的盐敏感性高血压中的作用及分子机制。方法在体实验选用2月龄盐敏感性高血压大鼠(dahl salt-sensitive,Dahl SS)25只随机分为三组:给予低盐(0.12%NaCl,LS)、高盐(8%NaCl,HS)和血小板抑制剂(8%NaCl+血小板抑制剂,HS+bus)处理6周。尾袖法检测大鼠动脉血压,流式细胞术分析外周血血小板活化率、血小板内Ca^(2+)浓度、血小板-白细胞聚集(platelet-leukocyte aggregation,PLA)和主动脉血管中免疫细胞的比例,ELISA方法检测血清炎症因子IL-6的表达。体外实验分离SD大鼠血小板,分为正常盐组(0.9%NaCl)和高盐组(1.3%NaCl),检测血小板内Ca^(2+)浓度和p-selectin表达的差异。结果与低盐组相比,高盐喂养的Dahl SS大鼠动脉血压明显升高,外周血血小板活化率、血小板-白细胞聚集的比例及主动脉血管免疫细胞的比例显著增多,血清炎症因子IL-6的水平明显增高;血小板抑制剂能够显著降低高盐引起的血压升高,抑制血小板活化,降低外周血PLA和主动脉血管免疫细胞的比例,并且减少外周血炎症因子IL-6的释放;体外分离纯化的大鼠血小板经高盐处理后,血小板内Ca^(2+)浓度增加,血小板表面p-selectin表达增多(P<0.05)。结论高盐通过活化血小板激活血管炎症参与了盐敏感性高血压的病理过程,其机制可能与高盐诱导血小板内Ca^(2+)浓度增加有关。但是,高盐如何导致血小板活化,以及血小板活化后如何通过炎症反应导致高血压的发生发展的具体机制还需要进一步研究。

Objective To investigate the role and mechanism of platelet in the development of salt-sensitive hypertension.Methods 25 Dahl salt-sensitive rats （Dahl SS） were divided into three groups： low-salt diet （0.12% NaCl, LS）, high-salt diet （8%NaCl, HS） and high-salt diet ＋ platelet inhibitor （8%NaCl＋busulfan, HS＋bus）.Blood pressures were measured by tail-cuff method.After six weeks, animals were sacrificed.Platelet p-selectin expression, platelet cytosolic Ca^2＋ concentration, platelet-leukocyte aggregation （PLA） in peripheral blood, and immune cells infiltrated on aortic walls were assessed by flow cytometry, and serum IL-6 level was tested by ELISA in vivo.Platelets purified from SD rats were treated with normal salt （0.9%NaCl） and high salt （1.3%NaCl）, then the cytosolic Ca^2＋ concentration and p-selectin expression of platelet were detected.Results We found that Dahl SS rats with high-salt diet, relative to low-salt diet, presented with high blood pressure and increased the ratio of platelet p-selectin expression, Ca^2＋ concentration.IL-6 level and PLA in peripheral blood, and the number of infiltrated immune cells on aortic walls were also significantly elevated in high-salt diet group.The whole events were ameliorated by the platelet inhibitor busulfan.Cytosolic Ca^2＋ concentration and p-selectin expression were also increased in purified platelets treated with high salt than those treated with low salt （P 〈 0.05）.Conclusions Our findings suggest that high salt induced platelet activation with increased Ca^2＋ concentration may play an important role in the development of salt-sensitive hypertension via vascular inflammation.However, the detailed mechanisms of platelet activation and development of high blood pressure via inflammation induced by high salt intake remain to be determined.