II型肺细胞基底外侧膜上的氯化钠协同转运

Sodium chloride cotransport at the basolateral membrane of type II pneumocytes.

作者信息

Shabarek F, Xu F, Oelberg D G

机构信息

Department of Pediatrics, University of Texas Medical School at Houston 77030.

出版信息

Biochem Med Metab Biol. 1994 Jun;52(1):76-83. doi: 10.1006/bmmb.1994.1036.

DOI:10.1006/bmmb.1994.1036

PMID:7917470

Abstract

Current evidence indirectly supports the hypothesis that Na+/Cl- cotransport occurs at basolateral membranes of type II pneumocytes. To test this hypothesis, enriched apical and basolateral plasma membrane vesicles were prepared from adult bovine type II pneumocytes. Uptake of 22Na+ or 36Cl- by these vesicle populations was monitored over time. Using enriched basolateral vesicles, substitution of formate- for Cl- nearly eliminated 22Na+ uptake, and substitution of Tris+ for Na+ significantly reduced 36Cl- uptake. These observations of Cl(-)-dependent 22Na+ uptake and Na(+)-dependent 36Cl- uptake demonstrated coupling between Na+ and Cl- absorption at the basolateral membrane. Na+/Cl- cotransport inhibitors, furosemide (1 mM) and bumetanide (0.1 mM), also reduced 22Na+ and 36Cl- uptakes by enriched basolateral vesicles. By contrast, furosemide and bumetanide did not affect 22Na+ and 36Cl- uptakes by enriched apical vesicles. Collectively, these observations support localization of Na+/Cl- cotransport to the basolateral membranes of mature type II pneumocytes.

摘要

目前的证据间接支持了Ⅱ型肺泡上皮细胞基底外侧膜存在Na⁺/Cl⁻协同转运的假说。为验证这一假说，从成年牛Ⅱ型肺泡上皮细胞制备了富集的顶端和基底外侧质膜囊泡。随着时间的推移监测这些囊泡群体对²²Na⁺或³⁶Cl⁻的摄取。使用富集的基底外侧囊泡，用甲酸根替代Cl⁻几乎消除了²²Na⁺摄取，用Tris⁺替代Na⁺显著降低了³⁶Cl⁻摄取。这些对Cl⁻依赖性²²Na⁺摄取和Na⁺依赖性³⁶Cl⁻摄取的观察结果表明，基底外侧膜上Na⁺和Cl⁻吸收之间存在偶联。Na⁺/Cl⁻协同转运抑制剂呋塞米（1 mM）和布美他尼（0.1 mM）也降低了富集的基底外侧囊泡对²²Na⁺和³⁶Cl⁻的摄取。相比之下，呋塞米和布美他尼不影响富集的顶端囊泡对²²Na⁺和³⁶Cl⁻的摄取。总体而言，这些观察结果支持Na⁺/Cl⁻协同转运定位于成熟Ⅱ型肺泡上皮细胞的基底外侧膜。