摘要
目的:观测大黄素对 Wistar 大鼠结肠环行平滑肌细胞胞质游离钙水平([Ca^(2+)]i)的影响,并探讨机制.方法:酶解法分离结肠环行平滑肌细胞,分别采用图像分析系统和激光扫描共聚焦显微镜观测细胞长度和[Ca^(2+)]i 的变化.结果:大黄素可收缩大鼠结肠环行平滑肌细胞,也可浓度依赖性升高[Ca^(2+)]i;大黄素作用后,[Ca^(2+)]i 迅速升高达到值([Ca^(2+)]i_(peak)),而后下降至平台期([Ca^(2+)]i_(Sustain),仍高于静息值).Nifedipine 对大黄素的钙动员作用没有明显影响,EGTA明显降低[Ca^(2+)]i_(Sustian).Heparine 几乎完全抑制[Ca^(2+)]i_(Peak),Ryanodine 明显抑制[Ca^(2+)]i_(Peak).结论:大黄素通过升高[Ca^(2+)]i 收缩结肠环行平滑肌细胞.大黄素升高[Ca^(2+)]i 的机制为:活化 IP3受体释放细胞内钙,进一步以 CICR 方式促进 RYR 受体开放,共同作用升高[Ca^(2+)]i,细胞外钙内流参与平台期[Ca^(2+)]i 的升高.
AIM:To investigate whether emodin has any effects on circular smooth muscle cells of rat colon and to examine the underlying mechanisms. METHODS:Smooth muscle cells were isolated from the circular muscle layers of Wistar rat colon and cell length was measured by computerized image micrometry.Intra- cellular Ca^(2+)([Ca^(2+)]i)signaling was studied in smooth muscle cells using Ca^(2+)indicator Fluo-3 AM by laser-scanning confocal microscopy. RESULTS:Emodin dose-dependently induced smooth muscle cells contraction,caused a large,transient increase in[Ca^(2+)]i followed by a sustained elevation in[Ca^(2+)]i.Emo- din-induced increase in[Ca^(2+)]i was unaffected by nifedipine,a votage-gated Ca^(2+)-channel antagonist,and the sustained phase of rising of[Ca^(2+)]i was attenuated by extracellular Ca^(2+)removal with EGTA solution.Inhibiting Ca^(2+)release from ryanodine-sensitive intracellular stores by ryanodine reduced the peak increase in [Ca^(2+)i.However, the application of heparine,an antagonist of IP_3R,nearly abolished the peak increase in [Ca^(2+)]i induced by emodin. CONCLUSION:Emodin has direct excitatory effect on cir- cular smooth muscle cells from rat colon and its effect is mediated through Ca^(2+)-dependent pathways.Furthermore, emodin-induced peak[Ca^(2+)]i increase may be attributable to the Ca^(2+)release from IP_3 sensitive stores,which pro- motes Ca^(2+)release from ryanodine-sensitive stores through CICR mechanism.Additionally,Ca^(2+)influx from extracellular medium contributes to the sustained increase in[Ca^(2+)]i.
出处
《世界华人消化杂志》
CAS
2003年第11期1699-1702,共4页
World Chinese Journal of Digestology
基金
国家自然科学基金
No.30171198
