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模拟失重大鼠肠系膜小动脉平滑肌细胞电压依赖性钙离子通道电流的改变

付兆君, 张立藩, 马进, 程宏伟

第四军医大学航空航天生理学教研室.陕西，西安 710032

摘要

该工作旨在探讨短、中期模拟失重下大鼠肠系膜小动脉血管平滑肌细胞（vascular smooth muscle cells, VSMCs）电压依赖性钙离子通道(voltage-dependent calcium channels, VDC)功能的改变。以尾部悬吊大鼠模型模拟失重对不同部位血管的影响。采用全细胞膜片钳实验技术，以Ba~(2+)作为载流子，测定1周及4周模拟失重大鼠肠系膜小动脉VSMCs VDC的电流密度、稳态激活与失活曲线及有关参数，并与对照组结果进行比较。研究表明，gai 实验所记录到的内向电流主要为钡离子通过长时程VDC（L-VDC）所形成的电流。与对照组相比，1周模拟失重大鼠肠系膜小动脉VSMCs L-VDC电流密度仅呈降低趋势；但4周模拟失重大鼠肠系膜小动脉VSMCs L-VDC电流密度则已显著降低。此外，与对照组相比，1、4周模拟失重大鼠肠系膜小动脉VSMCs的膜电容、翻转电位与L-VDC的一些动力学特征值，如通道的开放与关闭速率，通道电流稳态激活与失活曲线及其特征拟合参数V_(0.5)与k的值，均未见有显著改变。结果提示：模拟失重下后身小动脉VSMCs VDC功能降低可能也是模拟失重引起大鼠后身动脉收缩反应性降低及适应性萎缩变化的电生理机制之一。

关键词： 微重力; 飞行后心血管失调; 血管平滑肌细胞; 钙离子通道; 阻力性小动脉血管

Changes in voltage-dependent calcium channel currents of vascular smooth muscle cells isolated from small mesenteric arteries of simulated weightless rats

Fu Zhaojun, Zhang Lifan, Ma Jin, Cheng Hongwei

Department of Aerospace Physiology, Fourth Military Medical Univeristy.Xi'an 710032,Shaanxi

Abstract

The aim of the present study was to examine the changes in the function of voltage-dependent calcium channels (VDC) of vascular smooth muscle cells (VSMCs) isolated from small mesenteric arteries of rats subjected to 1-week or 4-week simulated weightlessness. The whole-cell recording mode was used to record current densities and Ba~(2+) was used as charge carrier. Curves and fitting parameters describing steady-state activation and inactivation characteristics of VDC were thus obtained. The inward currents recorded from the VSMCs of small mesenteric arteries were mainly the Ba~(2+) currents through the long-lasting type VDC (L-VDC). Compared with that of control rats, the L-VDC current density of VSMCs from small mesenteric arteries showed a trend toward a decrease in the rats after 1-week , while a significant decrease was observed in the rats after 4-week simulated weightlessness. However， there were no significant differences in the opening and closing rates of L-VDCs, the position of steady-state activation and inactivation curves, and in the parameters, V_(0.5) and k, between either of the two groups and its respective control group. The membrane capacitance and the reversal potential of the VSMCs from the small mesenteric arteries of rats after simulated weightlessness also showed no significant changes. These findings suggest that the decreased function of the L-VDC in hindquarter VSMCs might be one of the electrophysiological mechanisms that mediate the depressed vasoreactivity and atrophic change in hindquarter arteries during adaptation to simulated weightlessness in rats.

Key words: Microgravity;Postflight cardiovascular deconditioning;Vascular smooth muscle cells;Calcium channels;Small resistance arteries

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引用本文：

付兆君, 张立藩, 马进, 程宏伟. 模拟失重大鼠肠系膜小动脉平滑肌细胞电压依赖性钙离子通道电流的改变[J]. 生理学报 2005; 57 (1): .

Fu Zhaojun, Zhang Lifan, Ma Jin, Cheng Hongwei. Changes in voltage-dependent calcium channel currents of vascular smooth muscle cells isolated from small mesenteric arteries of simulated weightless rats. Acta Physiol Sin 2005; 57 (1): (in Chinese with English abstract).