{"title":"Active chloride transport powered by Na-K-ATPase in shark rectal gland.","authors":"F H Epstein, P Silva, J Stoff","doi":"","DOIUrl":null,"url":null,"abstract":"<p><p>The isolated rectal gland of the spiny dogfish is a unique model for the study of active chloride transport. The gland is stimulated to secrete chloride agains an electrical and a chemical gradient when perfused in vitro by theophylline and/or dibutyryl cyclic AMP. Chloride secretion is depressed by ouabain which inhibits Na-K-ATPase. Thiocyanate and furosemide also inhibit chloride secretion but ethoxolamide, a carbonic anhydrase inhibitor, does not. Chloride transport is highly dependent on sodium concentration in the perfusate. The intracellular concentration of chloride in intact glands exceeds the level expected at electrochemical equilibrium, suggesting active transport of chloride into the cell. These features suggest a general hypothesis for chloride secretion in which the uphill transport of chloride into the cytoplasm is coupled through a membrane carrier to the downhill movement of sodium along its electrochemical gradient. The latter is maintained by the Na-K-ATPase pump while chloride is extruded into the duct by electrical forces.</p>","PeriodicalId":72742,"journal":{"name":"Current problems in clinical biochemistry","volume":"8 ","pages":"106-22"},"PeriodicalIF":0.0000,"publicationDate":"1977-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Current problems in clinical biochemistry","FirstCategoryId":"1085","ListUrlMain":"","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
The isolated rectal gland of the spiny dogfish is a unique model for the study of active chloride transport. The gland is stimulated to secrete chloride agains an electrical and a chemical gradient when perfused in vitro by theophylline and/or dibutyryl cyclic AMP. Chloride secretion is depressed by ouabain which inhibits Na-K-ATPase. Thiocyanate and furosemide also inhibit chloride secretion but ethoxolamide, a carbonic anhydrase inhibitor, does not. Chloride transport is highly dependent on sodium concentration in the perfusate. The intracellular concentration of chloride in intact glands exceeds the level expected at electrochemical equilibrium, suggesting active transport of chloride into the cell. These features suggest a general hypothesis for chloride secretion in which the uphill transport of chloride into the cytoplasm is coupled through a membrane carrier to the downhill movement of sodium along its electrochemical gradient. The latter is maintained by the Na-K-ATPase pump while chloride is extruded into the duct by electrical forces.
棘角鲨的离体直肠腺是研究活性氯离子转运的独特模型。当体外灌注茶碱和/或二丁基环AMP时,刺激腺体以电和化学梯度分泌氯化物。抑制na - k - atp酶的瓦阿因抑制氯化物分泌。硫氰酸盐和速尿也能抑制氯化物的分泌,但乙氧唑胺(一种碳酸酐酶抑制剂)则没有作用。氯化物转运高度依赖于灌注液中的钠浓度。完整腺体的细胞内氯化物浓度超过了电化学平衡时的预期水平,表明氯化物被主动运输到细胞内。这些特征提出了氯离子分泌的一般假设,即氯离子进入细胞质的上坡运输是通过膜载体与钠离子沿着其电化学梯度下坡运动相耦合的。后者由na - k - atp酶泵维持,而氯化物则被电力挤出管道。