血管紧张素Ⅱ对RIN—m细胞胰岛素分泌功能的影响及机制探讨

Effect of angiotensin Ⅱ on insulin secretion function of RIN-m cell and its mechanism

目的观察血管紧张素Ⅱ（AngⅡ）对RIN-mβ细胞胰岛素分泌的影响，探讨AngⅡ损伤β细胞功能的机制。方法RIN—m细胞以不同浓度AngⅡ（0．1、1、10、100nmol／L）干预24h后，用放射免疫法检测各组基础（3．3mmol／L）和葡萄糖（16．7mmol／L）刺激下RIN—m细胞胰岛素分泌量；RT—PCR和Western印迹分别检测解耦联蛋白2（UCP2）mRNA及蛋白的表达水平；荧光素酶生物发光法检测细胞内ATP含量；流式细胞仪检测线粒体膜电位和细胞内Ca^2＋浓度。结果（1）在低糖刺激下，各AngⅡ处理组RIN-m细胞胰岛素分泌差异无统计学意义（F=0．644，P=0．634）；在高糖刺激下，除0．1nmol／L AngⅡ组外，其余各组胰岛素分泌均显著低于空白对照组（F=118．528，P=0．000）。（2）与空白对照组相比较，各AngⅡ处理组的UCP2 mRNA和蛋白表达显著增加（F=1370，P=0．000；F=675．175，P=0．000）。（3）与空白对照组相比较，除0．1nmoL／L AngⅡ组外，其余各组的RIN—m细胞线粒体膜电位、细胞内ATP含量和Ca^2＋浓度显著减少（F=4．035，P=0．008；F=3．353，P=0．013；F=5．867，P=0．001）。结论AngⅡ损伤胰岛β细胞葡萄糖刺激的胰岛素分泌（GSIS）功能，其机制可能是AngⅡ上调β细胞UCP2表达，进而降低线粒体膜电位、减少细胞内ATP含量及Ca^2＋浓度，最终损伤β细胞胰岛素分泌功能。

Objective To investigate the effect of angiotenisn Ⅱ （Ang Ⅱ） on RIN-m β-cell,and to explore the mechanism of β-cell function impairment caused by Ang Ⅱ.Methods RIN-m cells were cultured with various concentrations of Aug Ⅱ（0. 1,1,10,100 nmol/L）. After incubation for 24 hours, the basal （ 3.3 mmol/L） and glucose-stimulated（ 16.7 mmol/L） insulin secretion（GSIS） were detected by radioimmunoassay, mRNA and protein expressions of uncoupling protein 2 （UCP2） were determined by RT-PCR and Western blot, respectively. The intracellular ATP content was measured by luciferase bioluminescence. The mitochondrial membrane potential and cellular Ca^2＋ concentration were detected by flow cytometry. Results （ 1 ） Various concentrations of Ang Ⅱ had no significant influence on the basal insulin secrection of RIN-m cell（F=0. 644,P=0. 634）. Except for 0. 1 nmol/L Aug Ⅱ , the other concentrations of Ang Ⅱ markedly reduced GSIS of RIN-m cells（ F= 118. 528,P=0.000）. （2） Compared with the control group, Ang Ⅱ significantly increased mRNA and protein expression of UCP2 （F = 1 370, P= 0.000 ; F = 675. 175, P = 0.000）. （ 3 ） Except for 0. 1 nmol/L Ang Ⅱ , the other concentrations nf Aug Ⅱ significantly decreased the mitochondrial membrane potential, cellular ATP content, and cellular Ca^2＋ concentration ofRIN-mcell（F=4.035,P=0.008;F=3.353,P=0. 013;F=5.867,P=0. 001）. Conclusion AngⅡ impairs GSIS of β-cell,the mechanism of impairment may be interpreted that Ang Ⅱ can increase the expression of UCP2, furthermore,it can reduce mitochondrial membrane potential, decrease the eontent of cellular ATP and the concentration of cellular Ca^2＋ , can finally impair the function of -cell.