血管紧张素Ⅱ致心肌肥大小鼠模型中内源性二氧化硫体系的变化

Changes in endogenous sulfur dioxide pathway in angiotensin Ⅱ - induced myocardial hypertrophy in mice

目的探讨在血管紧张素Ⅱ（Ang Ⅱ）致心肌肥大小鼠模型中内源性二氧化硫（SO2）体系的变化。方法将9周龄健康C57BL小鼠14只按随机数字表法随机分为对照组及Ang Ⅱ组，每组7只，在背部皮下分别植入预装9 g/L盐水和Ang Ⅱ的胶囊渗透压泵。给药2周后，断颈处死小鼠。检测2组小鼠全心质量/体质量（HW/BW）及左心质量/全心质量（LVW/HW），苏木精-伊红染色法（HE）染色，在光学显微镜下观察心肌细胞显微结构变化，免疫组织化学法检测心肌标志分子α肌球蛋白重链（α-MHC）表达，Western blot检测α-MHC及SO2生成酶天门冬氨酸氨基转移酶1（AAT1）及AAT2表达的变化，采用高效液相色谱荧光法及比色法分别检测左心室心肌SO2水平及AAT活性。结果与对照组相比，Ang Ⅱ组小鼠HW/BW及LVW/HW均显著增大（均P〈0.01）；心肌细胞面积及直径增大，细胞质α-MHC蛋白阳性表达减弱；Western blot结果显示α-MHC和AAT2表达均明显减少（均P〈0.05）；小鼠心肌SO2水平降低[（1.093±0.131） μmol/g蛋白比（0.737±0.233） μmol/g蛋白，P〈0.01]，AAT活性降低[（7.979±1.317） U/mg蛋白比（6.470±0.516） U/mg蛋白，P〈0.05]；小鼠LVW/HW与心肌SO2水平呈负相关（r＝－0.56，P〈0.05）。结论Ang Ⅱ诱导小鼠心肌肥大模型中，心肌组织内源性SO2/AAT2体系显著下调。

Objective To explore the changes in the endogenous sulfur dioxide （SO2） pathway in the myocardial hypertrophy induced by the angiotensin Ⅱ （Ang Ⅱ ） in mice. Methods Fourteen healthy C57BL mice,9 weeks old, were randomly divided into control group（ n = 7） and Ang Ⅱ group （n = 7 ）, and capsule osmotic pump with pre - loaded 9 g/L saline and Ang Ⅱ was implanted into the back of each mouse subcutaneously. After 2 weeks, the mice were executed. The heart weight/body weight （HW/BW） and the left heart weight/full heart weight （LVW/HW） of the mice were measured. The microstructure of the cardiac myocyte was observed by hematoxylin - eosin （HE） staining under the microscope. The expression of myocardial alpha myosin heavy chain （ α - MHC） was detected by immunohis- tochemistry and Western blot methods. SO2 enzymes aspartate aminotransferase 1 （ AAT1 ） and AAT2 protein expression were detected by Western blot method. Myocardial SO2 content and AAT activity were measured by high performance liquid chromatography with fluorimetric detection and colometric method. Results Compared with control group, the HW/BW and LVW/HW in mice of Ang Ⅱ group were significantly increased （ all P 〈 0.01 ）, the cardiac myocytes were hypertrophy, and α - MHC positive staining in the cytoplasm of myocardium was weakened. Moreover, Western blot data showed that α - MHC protein expression in heart tissue of Ang Ⅱ- treated mice was decreased significantly （ all P 〈 0.05 ）. Simultaneously, the data showed that AAT2 protein expression, SO2 content and AAT activity in heart tissue of Ang Ⅱ -treated mice were also decreased markedly[ （1. 093 ±0. 131 ） μmol/g protein vs. （0.737 ±0.233 ） μmol/g protein,P 〈0.05 ; （7. 979 ±1. 317） U/mg protein vs. （6. 470 ± 0. 516） U/mg protein,P 〈 0.01 ]. Furthermore,there was a negative correlation between LVW/HW and cardiac SO2 content in heart tissue （ r = - 0.56, P 〈 0.05 ）. Conclusions Myocardial endogenous SO2/AAT2 pathway is down - regulated in the development of myocardial hypertrophy induced by Ang Ⅱ in mice.