Basolateral membrane Cl-, Na+-, and K+-coupled base transport mechanisms in rat MTALH
Basolateral membrane Cl-, Na+-, and K+-coupled base transport mechanisms in rat MTALH
复制标题
DOI：
10.1152/ajprenal.00220.2000
复制
发表时间：
2002-04-01
影响因子：
4.2
通讯作者：
Houillier, P
中科院分区：
文献类型：
--
作者：
Bourgeois, S;Massé, S;Houillier, P
在体外微灌注大鼠Henle髓厚升肢（MTALH）中，通过微荧光监测细胞ph，研究了参与基底外侧HCO3-运输的机制。去除管周Cl-诱导细胞碱化，在管周4,4'-二异硫氰二苯乙烯-2,2'-二磺酸（DIDS）存在时被抑制，在没有外部CO2/HCO3-的情况下被钝化。去除管周Cl-引起的碱化在双侧无Na+时持续存在，并伴有电压钳。当在无氯溶液中进行研究时，降低管周pH值会引起碱外排，这种外排被管周DIDS或缺乏外部CO2/HCO3-所抑制。去除小管周围Na+引起细胞酸化，这是通过刺激DIDS和乙基异丙基酰胺（EIPA）不敏感的Na+/HCO3-共转运和抑制基底侧Na+/H+交换来解释的。增加K+诱导细胞内碱化，在没有外部CO2/HCO3-的情况下被抑制。在2 mM处，管周Ba2+抑制K+- cl -共转运，没有引起上皮电压的任何变化，但引起细胞碱化，并抑制K+诱导的细胞碱化，这与碱性，电中性Ba2+敏感的K+- cl -共转运的存在一致，可能作为K+- hco3 -共转运。在管周存在呋塞米、[（二氢独立基）氧]烷酸、5-硝基-2-（3-苯基丙胺）苯甲酸酯或DIDS时，这种共转运被抑制。在生理条件下，至少有三种不同的基底侧HCO3-转运机制起作用：电中性Cl-/HCO3-交换，DIDS和eipa不敏感的Na+-HCO3-共转运，以及Ba2+敏感的电中性K+-Cl-(HCO3-)共转运。
Mechanisms involved in basolateral HCO3- transport were examined in the in vitro microperfused rat medullary thick ascending limb of Henle (MTALH) by microfluorometric monitoring of cell pH. Removing peritubular Cl- induced a cellular alkalinization that was inhibited in the presence of peritubular 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) and blunted in the absence of external CO2/HCO3-. The alkalinization elicited by removing peritubular Cl- persisted in the bilateral absence of Na+, together with a voltage clamp. When studied in Cl--free solutions, lowering peritubular pH induced a base efflux that was inhibited by peritubular DIDS or by the absence of external CO2/HCO3-. Removing peritubular Na+ elicited a cellular acidification that was accounted for by stimulation of a DIDS- and ethylisopropylamiloride (EIPA)-insensitive Na+/HCO3- cotransport and inhibition of a basolateral Na+/H+ exchange. Increasing bath K+ induced an intracellular alkalinization that was inhibited in the absence of external CO2/HCO3-. At 2 mM, peritubular Ba2+, which inhibits the K+-Cl- cotransport, did not induce any change in transepithelial voltage but elicited a cellular alkalinization and inhibited K+-induced cellular alkalinization, consistent with the presence of a basolateral, electroneutral Ba2+-sensitive K+-Cl- cotransport that may operate as a K+-HCO3- cotransport. This cotransport was inhibited in the peritubular presence of furosemide, [(dihydroindenyl)oxy] alkanoic acid, 5-nitro-2-(3-phenylpropylamino) benzoate, or DIDS. At least three distinct basolateral HCO3- transport mechanisms are functional under physiological conditions: electroneutral Cl-/HCO3- exchange, DIDS- and EIPA-insensitive Na+-HCO3- cotransport, and Ba2+-sensitive electroneutral K+-Cl-(HCO3-) cotransport.