15-HETE影响大鼠脑动脉平滑肌细胞内钙离子浓度的机制

目的 观察15-羟化二十烷四烯酸(15-HETE)对脑动脉平滑肌细胞内钙离子浓度([Ca2+]i)的影响,进一步探讨15-HETE引起[Ca2+]i变化的钙来源,从而明确15-HETE引起脑动脉平滑肌收缩的机制. 方法 酶法分离大鼠脑动脉平滑肌细胞,分为15-HETE组与对照组,15-HETE组添加15-HETE处理;对照组正常培养,不做其他处理.激光共聚焦技术测定15-HETE对[Ca2+]i的影响;进一步通过阻断外钙内流和耗竭内钙,探明15-HETE引起钙动员的来源;应用血管环技术从功能上判定细胞外钙对15-HETE引起的颈内动脉环收缩有无影响. 结果 15-HETE组与对照组相比,[Ca2+]i明显增加,差异有统计学意义(P＜0.05);预先加入硝苯地平、镧离子及改用无钙液阻断外钙内流后,15-HETE组[Ca2+]i仍明显高于对照组,差异有统计学意义(P＜0.05);而预先加入咖啡因耗竭细胞内钙后,15-HETE组[Ca2+]i较对照组差异无统计学意义(P＞0.05);采用无钙液去除细胞外钙后,15-HETE引起的血管环张力增加与有钙液中比较差异无统计学意义(P＞0.05). 结论 15-HETE可通过促使内钙释放而使[Ca2+]i增加,进而引起大鼠脑动脉平滑肌收缩.

Effect of 15-hydroxyeicosatetraenoic acid on calcium ion concentration of cerebral arterial smooth muscle cells in rats

Objective To observe the effect of 15-hydroxyeicosatetraenoic acid (15-HETE) on the intracellular calcium ion ([Ca2+]i) concentration of cerebral arterial smooth muscle and discuss the source of ([Ca2+]i) mobilization induced by 15-HETE to reveal the mechanism underlying the vasoconstriction aroused by 15-HETE. Methods First, papain and collagenase were employed to isolate the cerebral artery smooth muscle cells (SMCs) from the rats. The cells were separated into experimental group (treated with 15-HETE) and control group. Confocal laser scanning microscope was used to investigate the ([Ca2+]i) signaling in cultured SMCs. Then, Ca2+ channel blockers and Ca2+ store depletion agent were added to identify the source of Ca2+ transients in SMCs of the 2 groups. Finally, internal carotid artery (ICA) rings were used to observe the effect of non-Ca2+ solution on 15-HETE-induced ICA vasoconstriction on both groups. Results Compared with the control group, 15-HETE treatment group enjoyed a significantly increased level of ([Ca2+]i) in cultured SMCs (P＜0.05). After the addition of Ca2+channel blockers (nifedipine, lanthanum ion) and calcium-free solution, 15-HETE treatment group still enjoyed a significantly increased level of ([Ca2+]i) in cultured SMCs as compared with the control group (P＜0.05), while after the addition of Ca2+ store depletion agent (caffeine), no obvious difference was noted between the 2 groups (P＞0.05). Non-Ca2+ solution had no effect on 15-HETE induced vasoconstriction.Conclusion 15-HETE may activate Ca2+ releasing from intracellular stores to rise. ([Ca2+]i) level in SMCs, which subsequently induce the constriction of cerebral arterial smooth muscle.