【作者】 马恒；

【导师】 周士胜；

【作者基本信息】 中国人民解放军第四军医大学 ， 生理学， 2003， 硕士

【摘要】 血管是心血管系统的重要组成部分。血管张力的变化直接影响机体的血压水平。血管张力的维持与血管平滑肌细胞上的离子通道密切相关。阴离子通道(也被称为Cl~-通道)在心血管系统中有广泛地表达。研究表明，阴离子通道是维持心脏和血管活动的重要因素。本课题利用去甲肾上腺素引起的血管收缩模型，通过常规离体血管灌流技术研究了阴离子通道对血管张力的调节及其机制。 主要研究内容： 1．观察阴离子通道阻断剂对血管的舒张作用。 2．观察不同的离子替代后血管张力的变化。 3．观察容积敏感性氯离子通道对血管张力的调节作用。 4．观察阴离子通道阻断剂对高钾引起的血管收缩的舒张作用。 第口旱巨大学硕士学玫论文 5．观察阴离子通道对血管平滑肌外钙内流和内钙释放的影响。 主要研究结果： 1．阴离子通道阻断剂NFA、NPPB可以抑制去甲肾上腺素引起的血管收缩。 二．用氯化胆碱和四甲基氯化按分别替代灌流液中的氯化钠后血管张力无明显变化，在此基础上NFA、NPPB仍能抑制血管收缩，引起血管完全舒张；用通透性低的阴离子谷氨酸根和葡萄糖酸根分别替代灌流液中的Q后血管发生舒张；用通透性高的阴离子Br－和SCN－分别替代灌流液中的CI后血管张力增加，并能被NFA、NPPB所抑制。 3．渗透压变化可以影响阴离子通道的活动状态。在高渗环境中血管张力轻度下降。在此基础上，阴离子通道阻断剂NFA、NPPB舒血管效应减弱；在低渗环境中血管张力进一步增加，并能被NFA、NPPB所完全抑制。 4．阴离子通道阻断剂NFA、NPPB都能够抑制由 60 mmol／LKCI引起的血管收缩。 5．使用ifedipine预处理血管，阻断细胞外钙离子内流，将血管置于含 60mmol／L KCI的高钾环境中，血管不发生收缩。使用细胞内钙耗竭剂thapisin呷in预处理血管，耗竭细胞肌浆网内储存的钙离子。将血管处于含 60nunol／L KCI的高钾环境中，血管发生收缩。而阴离子通道阻断剂NFA、NPPB可以抑制此收缩。 6．NE可以引起处于细胞外液无钙环境中的血管收缩。而阴离子通道阻断剂NFA、NPPB可以抑制此收缩。 上述结果提示： DePartment ofh叭icb刃4 第口旱巨大学硕士学位论不 1．阴离子通道对维持血管张力有重要作用 2．细胞外液中Na＋的存在与否对NE引起的血管收缩无明显影响。 3．阴离子通道的活动状态对血管张力有显著影响。 4．阴离子通道的激活不依赖于细胞内钙离子的释放。 5．阴离子通道对血管平滑肌细胞外钙内流和内钙释放都有调节作用。 本研究表明，血管张力的维持可能主要与阴离子通道的活动状态有关。阴离子通道很可能是通过调节血管平滑肌细胞外钙内流和内钙释放两个途径来发挥调节血管张力的作用。这一发现为阐明盐与高血压的关系提供了新的实验依据。更多还原

【Abstract】 Vascular tone plays a key role in the maintenance of blood pressure. Anion channels are extensively expressed in the cardiovascular system, but their roles in the modulation of vascular tone are poorly understood. We, therefore, investigated the role of anion channels on the vascular tone. Norepinephrine (NE)-evoked contraction was observed in rat aorta by using routine blood vascular perfusion in vitro. The experimental designs were as follows:1. Vasorelaxing effects of anion channel blocker were observed.2. The change of vascular tone was observed after different ion substitution.3. Role of volume-regulated Cl channels(VRCC, Ic1.vol) on vascular tone was observed.4. Effects of anion channel blocker on contraction induced by KC1 (60 mmol/L) were observed.5. Effects of anion channels on the influx of extracellular calcium and the release of intracellular calcium were observed. The major results were summarized below:1. The anion channel blockers niflumic acid (NFA) and 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) produced inhibitory effects on NE-evocked contraction in the aorta.2. NE-evoked contraction was not significantly changed after the extracellular Na+ was replaced by choline and C4H12N+, but was relaxed when the extracellular Cl- was replaced by glutamate and gluconate. Moreover, the vasoconstriction induced by NE was further enhanced with the replacement of the extracellular Cl" by Br" and SCN", which was still sensitive to either NFA or NPPB.3. NE-evoked contraction was decreased in hypertonic solution, and vasorelaxing effect of anion channel blocker was attenuated compared with those in normal Tyrode solution. However, the constriction induced by NE was further enhanced when exposure of the aorta to hypotonic solution, which was inhibited by either NFA or NPPB.4. Contraction induced by 60 mmol/L KC1 was completely inhibited by NFA and NPPB.5. After pretreated with nifedipine to block the influx of extracellular calcium, the vessels did not contract when they were stimulated by 60 mmol/L KC1 solution; On the other hand, after pretreated with thapsigargin to deplete the intracellular calcium stores, the vessel remained the ability to contract when stimulated by 60mmol/L KCl solution. The anion channel blockers NFA and NPPB abolished the KCl-induced contraction of vessels which were pretreated by thapsigargin.6. The anion channel blockers NFA and NPPB inhibited the NE -induced contraction of vessels in Ca2+-free solution.These results suggest: 1) Anion channels play an important role in the regulation of blood vascular tone; 2) NE-stimulated contraction is not influenced by extracellular sodium; 3) Vascular tone can be affected by anion channel’s activity; 4) The activation of anion channels do not depend on release of intracellular calcium; 5) Anion channels may be involved in the regulation of vascular tone through modulating the influx of extracellular calcium and the release of intracellular calcium.In conclusion, anion channels play an important role in the regulation of blood vascular tone. Anion channels affect vascular tone through modulating the influx of extracellular calcium and the release of intracellular calcium, which provide new insight into the understanding of salt-sensitivity hypertension.更多还原