SODIUM-DEPENDENT NUCLEOSIDE TRANSPORT IN RABBIT INTESTINAL EPITHELIUM

被引:35
作者
RODEN, M
PATERSON, ARP
TURNHEIM, K
机构
[1] UNIV VIENNA,INST PHARMAKOL,WAHRINGER STR 13A,A-1090 VIENNA,AUSTRIA
[2] UNIV ALBERTA,MCEACHERN LAB,CANC RES GRP,EDMONTON T6G 2E1,ALBERTA,CANADA
关键词
D O I
10.1016/0016-5085(91)90652-2
中图分类号
R57 [消化系及腹部疾病];
学科分类号
摘要
Cellular uptake of formycin B, a poorly metabolized analog of inosine, by the isolated epithelium of rabbit jejunum is three times higher in the presence of Na+ than without this cation. The Na+-dependent nucleoside transport system is located in the apical membrane of the enterocytes and is capable of uphill transport, as shown for formycin B and adenosine with brush border membrane vesicles. According to present and earlier evidence, nucleoside transport across the basolateral membrane appears to have the properties of facilitated diffusion. Na+-dependent formycin B transport activity in intestinal epithelium decreases from jejunum to ileum and is absent in descending colon. As with Na+ -coupled cotransport systems for other organic solutes, apical entry of formycin B is driven by the electrochemical Na+ gradient into the cell. In contrast to the facilitated diffusion system for nucleosides, Na+ -dependent formycin B transport is not inhibited by nitrobenzylthioinosine, but both carrier systems are sensitive to inhibitors of d-glucose transport. Natural purine nucleosides and uridine are strong inhibitors of Na+-dependent formycin B transport. Trans-epithelial flux measurements substantiated that the Na+ -dependent transport mechanism for formycin B functions as an absorptive system. © 1991.
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页码:1553 / 1562
页数:10
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