缺氧对大鼠培养脑毛细血管内皮细胞中钠-钾-氯共转运体的影响。

Effect of hypoxia on Na(+)-K(+)-Cl- cotransport in cultured brain capillary endothelial cells of the rat.

作者信息

Kawai N, McCarron R M, Spatz M

机构信息

Stroke Branch, NINDS, NIH, Bethesda, Maryland 20892-4128, USA.

出版信息

J Neurochem. 1996 Jun;66(6):2572-9. doi: 10.1046/j.1471-4159.1996.66062572.x.

DOI:10.1046/j.1471-4159.1996.66062572.x

PMID:8632184

Abstract

The effect of hypoxia on Na+, K(+)-ATPase and Na(+)-K(+)-Cl- cotransport activity in cultured rat brain capillary endothelial cells (RBECs) was investigated by measuring 86Rb+ uptake as a tracer for K+. RBECs expressed both Na+, K(+)-ATPase and Na(+)-K(+)-Cl- cotransport activity (4.6 and 5.5 nmol/mg of protein/min, respectively). Hypoxia (24 h) decreased cellular ATP content by 43.5% and reduced Na+, K(+)-ATPase activity by 38.9%, whereas it significantly increased Na(+)-K(+)-Cl- cotransport activity by 49.1% in RBECs. To clarify further the mechanism responsible for these observations, the effect of oligomycin-induced ATP depletion on these ion transport systems was examined. Exposure of RBECs to oligomycin led to a time-dependent decrease of cellular ATP content (by approximately 65%) along with a complete inhibition of Na+, K(+)-ATPase and a coordinated increase of Na(+)-K(+)-Cl- cotransport activity (up to 100% above control values). Oligomycin augmentation of Na(+)-K(+)-Cl- cotransport activity was not observed in the presence of 2-deoxy-D-glucose (a competitive inhibitor of glucose transport and glycolysis) or in the absence of glucose. These results strongly suggest that under hypoxic conditions when Na+, K(+)-ATPase activity is reduced, RBECs have the ability to increase K+ uptake through Na(+)-K(+)-Cl-cotransport.

摘要

通过测量作为钾离子示踪剂的⁸⁶Rb⁺摄取量，研究了缺氧对培养的大鼠脑毛细血管内皮细胞（RBECs）中Na⁺、K⁺-ATP酶和Na⁺-K⁺-Cl⁻协同转运活性的影响。RBECs同时表达Na⁺、K⁺-ATP酶和Na⁺-K⁺-Cl⁻协同转运活性（分别为4.6和5.5 nmol/mg蛋白质/分钟）。缺氧（24小时）使细胞ATP含量降低43.5%，并使Na⁺、K⁺-ATP酶活性降低38.9%，而在RBECs中它显著增加Na⁺-K⁺-Cl⁻协同转运活性49.1%。为了进一步阐明导致这些观察结果的机制，研究了寡霉素诱导的ATP耗竭对这些离子转运系统的影响。将RBECs暴露于寡霉素导致细胞ATP含量随时间下降（约65%），同时Na⁺、K⁺-ATP酶完全被抑制，且Na⁺-K⁺-Cl⁻协同转运活性协同增加（比对照值高100%）。在存在2-脱氧-D-葡萄糖（葡萄糖转运和糖酵解的竞争性抑制剂）时或在无葡萄糖的情况下未观察到寡霉素对Na⁺-K⁺-Cl⁻协同转运活性的增强作用。这些结果强烈表明，在缺氧条件下，当Na⁺、K⁺-ATP酶活性降低时，RBECs有能力通过Na⁺-K⁺-Cl⁻协同转运增加钾离子摄取。