豚鼠胆囊上皮细胞碳酸氢盐的电中性分泌

Electroneutral secretion of bicarbonate by guinea pig gallbladder epithelium.

作者信息

Winterhager J M, Stewart C P, Heintze K, Petersen K U

出版信息

Am J Physiol. 1986 Apr;250(4 Pt 1):C617-28. doi: 10.1152/ajpcell.1986.250.4.C617.

DOI:10.1152/ajpcell.1986.250.4.C617

Abstract

Transepithelial HCO3- movement in guinea pig gallbladder was investigated in vitro. Absorptive (JHCO3ms) and secretory (JHCO3sm) HCO3- fluxes, determined by use of the pH-stat method were approximately 1.0 and 2.1 mumol X cm-2 X h-1, respectively. The resultant net secretion equaled in magnitude, and balanced electrically, the excess in net absorption of Cl- over that of Na+ X JHCO3sm was dependent on luminal Cl- and serosal Na+; it was inhibited by mucosal 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS; 10(-3) M) and serosal ouabain (3 X 10(-5) M) but not by serosal amiloride (10(-3) M) and scarcely by bilateral methazolamide (10(-4) M). JHCO3ms was reduced by mucosal Cl- but enhanced by serosal Cl-; it was dependent on mucosal Na+ and inhibited by mucosal amiloride and bilateral methazolamide. Our findings are consistent with a model in which 1) serosal HCO3- enters the cell in cotransport with Na+ and is then extruded into the lumen by Cl-(-)HCO3- exchange at the apical membrane; 2) mucosal HCO3- enters the cell secondary to apical membrane Na+-H+ exchange and recycles into the lumen via Cl-(-)HCO3- exchange or is, to a lesser extent, absorbed across the basolateral membrane.

摘要

在体外研究了豚鼠胆囊的跨上皮HCO₃⁻转运。采用pH计法测定的HCO₃⁻吸收通量（JHCO₃ms）和分泌通量（JHCO₃sm）分别约为1.0和2.1 μmol·cm⁻²·h⁻¹。由此产生的净分泌量在数值上等于Cl⁻的净吸收量超过Na⁺的净吸收量的差值，并在电方面保持平衡。JHCO₃sm取决于管腔Cl⁻和浆膜Na⁺；它受到黏膜4-乙酰氨基-4'-异硫氰基芪-2,2'-二磺酸（SITS；10⁻³ M）和浆膜哇巴因（3×10⁻⁵ M）的抑制，但不受浆膜阿米洛利（10⁻³ M）的抑制，几乎也不受双侧甲巯咪唑（10⁻⁴ M）的抑制。JHCO₃ms受到黏膜Cl⁻的降低作用，但受到浆膜Cl⁻的增强作用；它取决于黏膜Na⁺，并受到黏膜阿米洛利和双侧甲巯咪唑的抑制。我们的研究结果与以下模型一致：1）浆膜HCO₃⁻与Na⁺协同转运进入细胞，然后通过顶端膜的Cl⁻⁻HCO₃⁻交换被挤出到管腔中；2）黏膜HCO₃⁻继发于顶端膜的Na⁺⁻H⁺交换进入细胞，并通过Cl⁻⁻HCO₃⁻交换再循环到管腔中，或者在较小程度上通过基底外侧膜被吸收。