细胞外钾离子浓度升高会导致人中性粒细胞发生钙依赖性形态改变，并促进刀豆球蛋白A帽化。

Increasing extracellular potassium causes calcium-dependent shape change and facilitates concanavalin A capping in human neutrophils.

作者信息

Roberts R L, Mounessa N L, Gallin J I

出版信息

J Immunol. 1984 Apr;132(4):2000-6.

Abstract

Stimulation of human polymorphonuclear leukocytes (PMN) by chemoattractants is associated with changes in membrane potential, and it has been speculated that these changes are important in PMN function. In the present study, human PMN isolated on Percoll gradients were exposed to extracellular K+ concentrations, which have been shown to depolarize PMN. Incubation of PMN at 37 degrees C for 15 min in 125 mM K+ increased the number that capped fluoresceinated concanavalin A (Con A) to 78% +/- 5.1 with 6.9% +/- 0.8 forming Con A caps in 5 mM K+ (p less than 0.001). In the absence of lectins, high K+ induced polarization of PMN shape with pseudopod and uropod formation (2.4% +/- 0.1 polarized in 5 mM K+ vs 83.4% +/- 1.0 polarized in 125 mM K+ p less than 0.001). Control studies, in which Na+ was decreased by substituting choline chloride or sucrose, indicated that the K+ effects were specific and not due to lowering of Na+. Increasing K+ also stimulated preferential secretion of the specific (secondary) granule constituents, caused significant mobilization of receptors for the peptide N-formyl-methionyl-leucyl-phenylalanine (fmet-leu-phe), and increased the number of PMN migrating in chemotactic assays. Unlike the capping of Con A and shape change, however, the increase in fmet-leu-phe binding, degranulation, and locomotion was not specific for raising extracellular K+ and occurred when choline chloride was substituted for sodium chloride, suggesting that these effects may be due to the lowering of Na+ or the changing of the Na+ to K+ ratio. In related studies designed to examine the mechanism of these K+-induced effects, shape change and Con A cap formation were inhibited by the absence of extracellular calcium or the presence of the calcium channel blockers, methoxyverapamil (100 microM), manganese (2 mM), or cobalt (2 mM), suggesting that the K+-induced changes depend on an influx of calcium. Thus, the increase of extracellular K+ induces calcium-dependent membrane changes in PMN similar to those seen when PMN are stimulated by a chemoattractant.

摘要

趋化因子刺激人类多形核白细胞（PMN）与膜电位变化有关，据推测这些变化对PMN功能很重要。在本研究中，通过Percoll梯度分离的人类PMN暴露于已被证明可使PMN去极化的细胞外K⁺浓度中。将PMN在37℃下于125 mM K⁺中孵育15分钟，使荧光素化伴刀豆球蛋白A（Con A）形成帽的细胞数量增加到78%±5.1%，而在5 mM K⁺中形成Con A帽的细胞为6.9%±0.8%（p<0.001）。在没有凝集素的情况下，高K⁺诱导PMN形态极化，形成伪足和尾足（在5 mM K⁺中极化的细胞为2.4%±0.1%，在125 mM K⁺中极化的细胞为83.4%±1.0%，p<0.001）。对照研究中，通过用氯化胆碱或蔗糖替代来降低Na⁺，结果表明K⁺的作用是特异性的，并非由于Na⁺降低所致。增加K⁺还刺激了特异性（次级）颗粒成分的优先分泌，导致肽N-甲酰甲硫氨酰-亮氨酰-苯丙氨酸（fmet-leu-phe）受体的显著动员，并增加了在趋化性测定中迁移的PMN数量。然而，与Con A的帽形成和形态变化不同，fmet-leu-phe结合、脱颗粒和运动的增加并非特异性地由细胞外K⁺升高引起，当用氯化胆碱替代氯化钠时也会发生，这表明这些效应可能是由于Na⁺降低或Na⁺与K⁺比例变化所致。在旨在研究这些K⁺诱导效应机制的相关研究中，细胞外钙缺乏或存在钙通道阻滞剂甲氧基维拉帕米（100 μM）、锰（2 mM）或钴（2 mM）时，形态变化和Con A帽形成受到抑制，这表明K⁺诱导的变化依赖于钙内流。因此，细胞外K⁺的增加诱导PMN中钙依赖性膜变化，类似于PMN受到趋化因子刺激时所观察到的变化。