中文摘要：

目的：研究洛沙坦（Los）能否抑制β-肾上腺素能刺激诱导的大鼠心肌细胞凋亡，及其抑制凋亡的作用机制。方法：体外培养大鼠H9c2心肌细胞株，将其分为对照组、异丙肾上腺素（ISO）组、ISO＋Los组、LY294002组和DMSO组，用流式细胞术和琼脂糖凝胶电泳观察心肌细胞的凋亡状态，通过RT—PCR检测凋亡相关基因的表达，Western blotting检测磷酸化Akt（P—Akt）和总Akt（t—Akt）蛋白水平的表达变化，放射免疫法检测各组细胞cAMP的含量。结果：10μmol／LISO可诱导H9c2心肌细胞凋亡，并伴有bax／bcl-2和caspase-9表达增高以及cAMP水平升高；加入10μmol／LLos后可明显抑制细胞凋亡的发生，bax／bcl-2和caspase-9表达减少，同时P—Akt的蛋白水平显著升高，而cAMP的水平降低；当加入LY294002阻断Akt活化后则可增加细胞凋亡的发生，从而取消Los对ISO诱导凋亡的保护作用。结论：ISO通过慢性刺激β-肾上腺素能受体（β—AR）可诱导心肌细胞凋亡，Los通过干扰β—AR下游信号转导通路并增加Akt活化，从而抑制β-肾上腺素能刺激诱导的心肌细胞凋亡。

英文摘要：

AIM： To investigate the protective effect of losartan （Los） on apoptosis of H9c2 cells induced by isoprenaline （ISO）, and to discover its related mechanism. METHODS： H9c2 ceils cultured on plastic plates were divided into control, ISO, ISO ＋ Los, ISO ＋ Los ＋ LY294002 and DMSO groups. Cell apoptosis was evaluated by flow cytometery and agarose gel electrophoresis. The mRNA levels of bax, bcl - 2 and caspase - 9 were detected by RT - PCR and the expressions of phosphorylated and total Akt （ p - Akt and t - Akt） were assessed by Western blotting. The cAMP was meas- ured by radioimmunoassay. RESULTS： ISO at concentration of 10 μmol/L induced apoptosis of H9c2 with an increase in bax/bcl - 2, caspase - 9 and cAMP. Addition of 10 μmol/L losartan inhibited apoptosis obviously with a decrease in bax/ bcl- 2, caspase- 9 and cAMP. A significant increase in p-Akt was observed, and its protein level was elevated. LY294002 at concentration of 1 μmol/L abolished the protective effects of losartan on ISO - induced apoptosis in H9c2 cells. CONCLUSION： ISO might induce H9c2 cell apoptosis through stimulation of β-adrenergic receptor （β -AR）. Los inhibits downstream signaling of β - AR, and promotes the activation of Akt. Subsequendy it might attenuate the apoptosis induced by β - adrenergie stimulation of ISO.