Association of granular exocytosis with Ca(2+)-activated K+ channels in human eosinophils.
Association of granular exocytosis with Ca(2+)-activated K+ channels in human eosinophils.
复制标题
颗粒胞吐作用与人嗜酸性粒细胞中 Ca(2) 激活的 K 通道的关联。
DOI：
10.1152/ajplung.1997.273.1.l16
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Leff,AR
中科院分区：
文献类型：
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作者：
Saito,M;Sato,R;Munoz,NM;Herrnreiter,A;Oyaizu,M;Kasugai,H;Narahashi,T;Leff,AR
我们研究了从轻度特应性供者中分离的嗜酸性粒细胞中由Ca（2+）激活的K+通道（KCa通道）引起的脱粒机制。用0.1 μ M血小板活化因子（PAF）刺激嗜酸性粒细胞引起单通道激活，如细胞贴附膜片钳技术所记录。这些通道是选择性渗透的K+，因为逆转电位接近K+的平衡电位。然而，通道是不渗透的Na+或Cl-的离子取代实验所证明的。钙离子载体A-23187，在1 μ M，增加的K+通道活性的存在下，在外部灌流液中的Ca 2+，但不诱导通道活性的情况下，Ca 2+。用另一种钙离子载体离子霉素（1 μ M）和Ca（2+）释放剂毒胡萝卜素（10 μ M）也得到了类似的结果。PAF和A-23187激活的K+通道具有相似的特性：单通道电导有两个水平，PAF为10 +/-1.5和22 +/-1.7pS，A-23187为11 +/-1.3和24 +/-1.9pS; PAF诱导的大电导通道的平均开放时间为1.45 ± 0.3ms，A-23187诱导的大电导通道的平均开放时间为1.26 ± 0.5ms。这些结果表明PAF激活KCa通道。奎尼丁可阻断A-23187引起的KCa电流和主要碱性蛋白释放。提示KCa通道与人嗜酸性粒细胞颗粒分泌有关。
We studied the mechanism of degranulation caused by Ca(2+)-activated K+ channels (KCa channels) in eosinophils isolated from mildly atopic donors using negative immunoselection. Stimulation of eosinophils with 0.1 microM platelet-activating factor (PAF) caused activation of single channels as recorded by the cell-attached patch-clamp technique. These channels were selectively permeable to K+ because the reversal potential was close to the equilibrium potential for K+. However, the channels were not permeable to Na+ or Cl- as demonstrated by ion substitution experiments. The calcium ionophore A-23187, at 1 microM, increased the K+ channel activity in the presence of Ca2+ in the external perfusate but did not induce channel activity in the absence of Ca2+. Similar results were obtained with another calcium ionophore, ionomycin (1 microM), and the Ca(2+)-releasing agent thapsigargin (10 microM). K+ channels activated by PAF and A-23187 had similar characteristics: two levels of single-channel conductances were observed, 10 +/- 1.5 and 22 +/- 1.7 pS as induced by PAF and 11 +/- 1.3 and 24 +/- 1.9 pS by A-23187; the mean open times of the large-conductance channels were 1.45 +/- 0.3 ms as induced by PAF and 1.26 +/- 0.5 ms by A-23187. These results indicate that PAF activates KCa channels. Both KCa currents and major basic protein release caused by A-23187 were blocked by quinidine. It is suggested that KCa channels are associated with granule secretion in human eosinophils.