薛军辉, 王小成, 高放, 白云刚, 张磊, 刘立, 张作明*
已有研究表明模拟失重可引起大鼠脑动脉发生区域特异性变化，其中Ca2+通道和肾素-血管紧张素系统(renin-angiotensin system, RAS)可能发挥着重要的作用。本研究旨在探讨血管紧张素II (angiotensin II, Ang II)对短期模拟失重大鼠脑基底动脉血管平滑肌细胞(vascular smooth muscle cells, VSMCs) L-型Ca2+通道(L-type calcium channel, CaL)功能的影响。模拟失重(尾部悬吊) 3 d后，用木瓜蛋白酶法分离大鼠脑基底动脉VSMCs。采用全细胞膜片钳技术，以Ba2+作为载流子，测定CaL电流密度，然后观察Ang II对该电流的影响。结果显示，模拟失重3 d对大鼠脑基底动脉VSMCs的膜电容和接入电阻无明显影响，但可致VSMCs的CaL电流密度显著增加。不过，模拟失重对CaL的电压激活特性和稳态激活曲线亦无明显影响。对照组和模拟失重组大鼠脑基底动脉VSMCs的CaL电流密度在给予Ang II处理后均显著增加，且模拟失重组的增加幅度显著大于对照组。以上结果提示，3 d短期模拟失重即可引起大鼠脑动脉VSMCs的CaL发生适应性改变，且可导致其对Ang II的反应性增强，表明Ang II可能在脑动脉失重适应性改变中起着一定的作用。
关键词： 微重力; 血管平滑肌细胞; Ca2+通道; 血管紧张素II
[Short-term simulated weightlessness enhances response of L-type calcium channel to angiotensin II in cerebral vascular smooth muscle cells in rats.] [Article in Chinese]
XUE Jun-Hui, WANG Xiao-Cheng, GAO Fang, BAI Yun-Gang, ZHANG Lei, LIU Li1, ZHANG Zuo-ming*
Departments of Clinical Aerospace Medicine and Aerospace Physiology, Key Laboratory of Aerospace Medicine of Ministry of Education, the Fourth Military Medical University, Xi’an 710032, China
Some studies suggest that the calcium channels and rennin-angiotensin system (RAS) play pivotal roles in the region-specific vascular adaptation due to simulated weightlessness. This study was designed to clarify if angiotensin II (Ang II) was involved in the adaptational change of the L-type calcium channel (Ca(L)) in the cerebral arterial vascular smooth muscle cells (VSMCs) under simulated weightlessness. Tail suspension (SUS) for 3 d was used to simulate immediate early cardiovascular changes to weightlessness. Then VSMCs in cerebral basilar artery were enzymatically isolated using papain, and Ca(L) current (barium instead of calcium as current carrier) in VSMCs was measured by whole-cell patch-clamp techniques. The results showed that 3-day simulated weightlessness significantly increased current density of Ca(L). However, I-V relationships of normalized peak current densities and steady-state activation curves of Ca(L) were not affected by simulated weightlessness. Although Ang II significantly increased current densities of Ca(L) in both SUS and control rats, the increase of Ca(L) current density in SUS rats was much more than that in control rats. These results suggest that 3-day simulated weightlessness induces the adaptational change of Ca(L) in cerebral VSMCs including increased response to Ang II, indicating that Ang II may play an important role in the adaptational change of cerebral arteries under microgravity.
Key words: weightlessness; vascular smooth muscle cells; calcium channels; angiotensin II
通讯作者：张作明 E-mail: email@example.com
薛军辉, 王小成, 高放, 白云刚, 张磊, 刘立, 张作明. 短期模拟失重可增强大鼠脑动脉平滑肌细胞L-型Ca2+通道对血管紧张素II的反应性[J]. 生理学报 2011; 63 (1): 81-88.
XUE Jun-Hui, WANG Xiao-Cheng, GAO Fang, BAI Yun-Gang, ZHANG Lei, LIU Li1, ZHANG Zuo-ming. [Short-term simulated weightlessness enhances response of L-type calcium channel to angiotensin II in cerebral vascular smooth muscle cells in rats.] [Article in Chinese]. Acta Physiol Sin 2011; 63 (1): 81-88 (in Chinese with English abstract).