Potassium ion fluxes in corneal epithelial cells exposed to UVB
Potassium ion fluxes in corneal epithelial cells exposed to UVB
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DOI：
10.1016/j.exer.2011.02.019
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发表时间：
2011-05-01
影响因子：
3.4
通讯作者：
Haarsma, Loren D.
中科院分区：
文献类型：
--
作者：
Ubels, John L.;Van Dyken, Rachel E.;Haarsma, Loren D.
本研究的目的是研究K（+）从暴露于环境水平的UVB的人角膜缘上皮细胞（HCLE）中的流出，已知这会导致细胞凋亡，并检查K（+）通道阻断剂对UVB诱导的钾丢失的影响。将HCLE细胞暴露于100-200 mJ/cm（2）UVB，然后在含有5.5-100 mM K（+）、BDS-1、Ba（2+）或哇巴因的培养基中孵育。为了测量细胞内阳离子，将细胞在280 mM蔗糖中洗涤并在DI水中裂解。通过离子色谱法测量裂解物中的K（+）和Na（+）水平。在暴露于UVB和5.5 mM K（+）培养基后10 min，HCLE细胞显示出K（i）（+）的最大损失，90 min后恢复正常K（+）水平。UVB暴露后用1 μ M BDS-1处理减少了HCLE细胞的K（+）损失。0.1-5 mM Ba（2+）处理可抑制UVB诱导的K（+）损失，并呈时间和剂量依赖性。这些结果证实，阻断暴露于UVB的HCLE细胞中的通道可防止K（+）流出，从而证实UVB激活这些细胞中的K（+）通道。电生理学数据显示，K（+）通道在UVB暴露后至少90分钟仍保持高度活跃。暴露于UVB并在0.01-1 μ M哇巴因中孵育的HCLE细胞不能从UVB诱导的K（+）损失中恢复。这些数据表明，Na/K泵可用于在UVB暴露后使HCLE细胞中的[K（+）]（i）恢复到对照水平，并且该泵不因暴露于UVB而受损。在含有25-100 mM K（+）培养基的培养基中孵育暴露于UVB的HCLE细胞，在细胞外浓度低至25 mM（泪液中的浓度）时阻止K（+）流出，维持K（i）（+）的控制水平。在所有实验中，内向通量和细胞内Na+水平反映了K（+）的变化，尽管预期浓度较低。25 mM K（o）（+）对UVB诱导的K（i）（+）损失的预防作用与泪液中相对较高的K（+）浓度对保护角膜上皮免受环境UVB影响的可能贡献一致。(c)2011爱思唯尔有限公司保留所有权利。
The goal of this study was to investigate the efflux of K(+) from human corneal limbal epithelial cells (HCLE) exposed to ambient levels of UVB, which is known to cause apoptosis, and to examine the effect of K(+) channel blockers on loss of potassium induced by UVB. HCLE cells were exposed to 100-200 mJ/cm(2) UVB, followed by incubation in culture media with 5.5-100 mM K(+), BDS-1, Ba(2+) or ouabain. To measure intracellular cations, cells were washed in 280 mM sucrose and lysed in DI water. K(+) and Na(+) levels in lysates were measured by ion chromatography. HCLE cells showed maximal loss of K(i)(+) 10 min after exposure to UVB and 5.5 mM K(+) media, with recovery of normal K(+) levels after 90 min. Treatment with 1 mu M BDS-1 following UVB exposure reduced the loss of K(+) by HCLE cells. Exposure to 0.1-5 mM Ba(2+) inhibited UVB-induced K(+) loss in a time and dose-dependent manner. These results confirm that blocking channels in HCLE cells exposed to UVB prevents efflux of K(+), confirming that UVB activates K(+) channels in these cells. Electrophysiology data show that K(+) channels remain highly active at least 90 min after UVB exposure. HCLE cells exposed to UVB and incubated in 0.01-1 mu M ouabain did not recover from UVB-induced K(+) loss. These data suggest that the Na/K pump may act to restore [K(+)](i) to control levels in HCLE cells following UVB exposure and that the pump is not damaged by exposure to UVB. Incubation of HCLE cells exposed to UVB in medium with 25-100 mM K(+) media prevented K(+) efflux at extracellular concentrations as low as 25 mM (the concentration in tear fluid), maintaining control levels of K(i)(+). In all experiments inward fluxes and intracellular Na+ levels mirrored K(+) changes, albeit at the expected lower concentrations. The prevention of UVB-induced K(i)(+) loss by 25 mM K(o)(+) is consistent with the possible contribution of the relatively high K(+) concentration in tears to protection of the corneal epithelium from ambient UVB. (c) 2011 Elsevier Ltd. All rights reserved.