敲除AT_(1a)基因对血管紧张素Ⅱ受体介导的信号传导作用

Effect of angiotensin II receptor subtype (AT la ) knockout on angiotensin II mediated calcium signal transduction pathways

目的研究敲除血管紧张素Ⅱ受体亚型（ＡＴ１ａ）基因对血管紧张素Ⅱ（ＡｎｇⅡ）信号传导的影响，明确ＡＴ１ａ在血管功能调节中的作用。方法应用缺乏ＡＴ１ａ基因小鼠的主动脉血管平滑肌细胞（ＶＳＭＣ），采用钙荧光分析技术，观察Ｇ蛋白受体偶联和酪氨酸激酶相关的钙离子信号传导通路的变化。结果敲除ＡＴ１ａ基因，并不影响ＡｎｇⅡ介导的ＶＳＭＣ钙增加，应用Ｇ蛋白拮抗剂和酪氨酸激酶抑制剂均能显著抑制ＡｎｇⅡ反应。结论敲除ＡＴ１ａ基因，其他ＡＴ１受体亚型能起明显的代偿作用，ＡＴ１ａ受体亚型受Ｇ蛋白和酪氨酸激酶信号传导通路共同调节。

Objective To investigate the effect of AT la gene knockout on angiotensin Ⅱ (Ang Ⅱ) mediated calcium signal transduction pathways and determine the role of AT la gene in the regulation of vascular function.Methods Vascular smooth muscle cells (VSMCs) were obtained from mice that mutant AT la gene and its wild type control. Intracellular calcium signal was observed using Fura 2/AM fluorescent technique. GDP βS and genestein were used to antagonize G protein and tyrosine kinase (TK) coupling pathways, respectively.Results Ang Ⅱ mediated calcium signal was ineffective after knockout AT 1a gene. Inhibition of G protein and TK can significantly reduce the response of calcium signal to Ang Ⅱ stimulation in VSMCs from mice.Conclusion Calcium signal was not interrupted by AT 1a gene knockout due to compensative effect of other AT 1 receptor subtype and AT 1 receptor subtypes were regulated by both G protein and TK coupling signal transduction pathways.