中文摘要：

目的：探讨尼古丁作用人脐带间充质干细胞（MSCs）前后，一氧化氮（NO）、细胞内钙离子（ca^2＋）的变化及α7nAchR的表达情况。方法：采用硝酸还原酶法检测不同质量浓度尼古丁作用于MSCs后24、36、48h，MSCs内NO的释放情况；尼古丁作用MSCs 24h，fluo-3／AM染色，流式细胞仪检测MSCs内ca……2＋变化；用RT-qPCR检测尼古丁作用后α7nAchR的表达情况。结果：尼古丁作用MSCs24、36h后，各实验组NO水平显著高于对照组（P〈0．05），呈时间、质量浓度依赖性，但在48h，质量浓度0．8与1．0mg／mL组，NO水平低于对照组。尼古丁作用后，各实验组质量浓度（0．6、0．8、1．0mg／mL）的ca^2＋荧光强度分别为（141．26±16．01）、（164．90±18．39）、（198．76±17．63），均高于对照组（119．30±14．14），其中质量浓度0．8、1．0mg／mL组与对照组相比有显著差异（P〈0．05）。MSCs可表达α7nAchR，且尼古丁作用后表达水平增高，呈时间浓度依赖性。结论：尼古丁可上调人脐带MSCs的α7nAchR表达，并通过刺激MSCs释放NO、升高细胞内Ca^2＋从而致MSCs凋亡。

英文摘要：

Aim：To explore the effects of nicotine on intracellular nitric oxide, Calcium ion and ex-pression of ot7nAchR in umbilical cord mesenchymal stem cells. Methods： MSCs were treated with dif-ferent concentrations of nicotine. The level of NO was detected by nitrate reductase method at 24,36,48h ;after cultured with nicotine for 2gh, cells were stained using by fluo-3/AM and the change of Ca^2＋ wasdetermined by flow cytometer. The expression of α7 nAchR was detected by Real-time Quantitative PCR.Results： After treated with nicotine, the nitric oxide level in each experimental group were significantlyhigher than that of the control group at 24h and 36h（ P 〈0. 05 ）, in a dose and time dependent manners,however at 48 h the levels of NO in 0. 8 mg/mL group andl. 0 mg/mL group were lower than the controlgroup, which may be related with the increased cells apoptosis. After treated with nicotine, the Ca^2＋ fluo-rescence intensity in each experimental group （ 0. 6, 0. 8, 1.0 mg/mL） were （ 141.26 ±. 16. 01 ）,（ 164. 90±18.39）, （ 198.76±17.63）, respectively,which were higher than the control group （ 119.30±14. 14）. The expression of otTnAchR was detected in MSCs, and was found to be up-regulated aftertreated with nicotine in a dose-dependent manner and a time-dependent manner. Conclusion：Nicotinecan promote MSCs apoptosis by up-regulating the expression of ct7nAchR, stimulating MSCs to releaseNO and elevating the intracellular Ca^2＋.