Kim M-J, Cheng G, Agrawal D K
Department of Biomedical Sciences, University School of Medicine, Omaha, NE 68178, USA.
Clin Exp Immunol. 2004 Dec;138(3):453-9. doi: 10.1111/j.1365-2249.2004.02635.x.
Increased adhesion and diapedesis of monocytes appear to be primary initiating factors in the pathophysiology of occlusive vascular diseases, including atherosclerosis and restenosis. However, the underlying mechanisms of transendothelial migration and invasion of monocytes into the blood vessels are not known. Alterations in ion channels on the cell membrane are generally involved in induced changes in shape and volume. In the present study, we investigated the expression and functional role of chloride channels in freshly isolated human blood monocytes. The Cl- currents in whole-cells were measured by the patch-clamp technique. We observed whole cell Cl- currents, which were time-independent and outwardly rectifying. The chloride channel blockers 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) and R(+)-[(6,7-dichloro-2-cyclopentyl-2,3-dihydro-2-methyl-1-oxo-1H-inden-5yl)-oxy]acetic acid 94 (IAA94) attenuated the Cl- currents. NPPB and IAA94 also inhibited chemotaxis of monocytes, as measured in Boyden chemotactic chambers, with the same sensitivity. NPPB but not IAA94, increased the cell volume as measured by shape change, and decreased tumour necrosis factor (TNF)-alpha-induced monocyte adhesion to endothelial cells. These results suggest that monocytes contain Cl- channels which regulate transendothelial migration of monocytes, due presumably to an alteration in cell volume.
单核细胞黏附增加和穿壁渗出似乎是包括动脉粥样硬化和再狭窄在内的闭塞性血管疾病病理生理学中的主要起始因素。然而，单核细胞经内皮迁移和侵入血管的潜在机制尚不清楚。细胞膜上离子通道的改变通常与细胞形状和体积的诱导变化有关。在本研究中，我们调查了新鲜分离的人血单核细胞中氯离子通道的表达及其功能作用。采用膜片钳技术测量全细胞中的氯离子电流。我们观察到全细胞氯离子电流，其不依赖时间且向外整流。氯离子通道阻滞剂5-硝基-2-(3-苯丙基氨基)苯甲酸(NPPB)和R(+)-[(6,7-二氯-2-环戊基-2,3-二氢-2-甲基-1-氧代-1H-茚-5-基)-氧基]乙酸94(IAA94)减弱了氯离子电流。在博伊登趋化小室中测量时,NPPB和IAA94也以相同的敏感性抑制单核细胞的趋化性。通过形状变化测量，NPPB而非IAA94增加了细胞体积，并减少了肿瘤坏死因子(TNF)-α诱导的单核细胞与内皮细胞的黏附。这些结果表明，单核细胞含有氯离子通道，可能由于细胞体积的改变，这些通道调节单核细胞的经内皮迁移。
