Biochemical, histological, and inhibitor studies of membrane carbonic anhydrase in frog gastric acid secretion.
Biochemical, histological, and inhibitor studies of membrane carbonic anhydrase in frog gastric acid secretion.
复制标题
青蛙胃酸分泌中膜碳酸酐酶的生化、组织学和抑制剂研究。
DOI：
10.1152/ajpgi.2001.281.1.g61
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Tu,C
中科院分区：
文献类型：
--
作者：
Swenson,ER;Tewson,TW;Wistrand,PJ;Ridderstrale,Y;Tu,C
胃酸分泌依赖于碳酸酐酶（CA）。为了确定膜结合CA的作用，我们在青蛙（Rana pipiens）中使用了生化、组织化学和药理学方法。在胃匀浆和微粒体中研究了膜渗透和非膜渗透的CA活性和抑制作用。测量组胺刺激的离体粘膜中H+的分泌，分别在粘膜添加渗透CA抑制剂（甲基唑胺）前后，以及在粘膜或浆膜中添加两种不同分子质量的渗透CA抑制剂前后：一种与氨基苯并胺和对氟酶-氨基苯并胺连接的聚合物（分子质量，454 kDa）。蛙胃黏膜CA总活性为2280 U/g，其中10%为膜结合CA， pH值低于4时，膜结合CA仍有可检测活性。组织化学上，在表面上皮细胞、氧合细胞和毛细血管内皮细胞中存在膜相关性CA。甲唑胺使H+的分泌减少100%，而两种不含H+的抑制剂在应用于粘膜侧时同样阻断分泌40%，应用于浆膜侧时同样阻断55%。细胞膜结合的CA存在于青蛙氧合细胞中，它对酸失活和不适当抑制剂抑制的相对抗性表明，它在顶端和基底侧都有酸分泌。
Gastric acid secretion is dependent on carbonic anhydrase (CA). To define the role of membrane-bound CA, we used biochemical, histochemical, and pharmacological approaches in the frog (Rana pipiens). CA activity and inhibition by membrane-permeant and -impermeant agents were studied in stomach homogenates and microsomal fractions. H+secretion in the histamine-stimulated isolated mucosa was measured before and after mucosal addition of a permeant CA inhibitor (methazolamide) and before and after mucosal or serosal addition of two impermeant CA inhibitors of differing molecular mass: a 3,500-kDa polymer linked to aminobenzolamide andp-fluorobenzyl-aminobenzolamide (molecular mass, 454 kDa). Total CA activity of frog gastric mucosa is 2,280 U/g, of which 10% is due to membrane-bound CA. Membrane-bound CA retains detectable activity below pH 4. Histochemically, there is membrane-associated CA in surface epithelial, oxynticopeptic, and capillary endothelial cells. Methazolamide reduced H+secretion by 100%, whereas the two impermeant inhibitors equally blocked secretion by 40% when applied to the mucosal side and by 55% when applied to the serosal side. The presence of membrane-bound CA in frog oxynticopeptic cells and its relative resistance to acid inactivation and inhibition by impermeant inhibitors demonstrate that it subserves acid secretion at both the apical and basolateral sides.