CHARACTERISTICS OF THE TRANSPORT OF OXALATE AND OTHER IONS ACROSS RABBIT PROXIMAL COLON

被引:34
作者
HATCH, M
FREEL, RW
VAZIRI, ND
机构
[1] Division of Nephrology, Department of Medicine, University of California at Irvine, Irvine, 92717, CA
来源
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY | 1993年 / 423卷 / 3-4期
关键词
ABSORPTION; SECRETION; CAMP; EPINEPHRINE; SODIUM; CHLORIDE; TRANSPORT INHIBITORS;
D O I
10.1007/BF00374396
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
In order to characterize oxalate handling by the P2 segment of the rabbit proximal colon, the fluxes of [C-14]oxalate, Na-22+, and Cl-36- were measured in vitro using conventional short-circuiting techniques. In standard buffer the proximal colon exhibited net secretion of Na+ (-2.31 +/- 0.64 muequiv cm-2 h-1), negligible net Cl- transport, and net secretion of oxalate (-12.7 +/- 1.6 pmol cm-2 h-1). Replacement of buffer Na+ or Cl- abolished net oxalate secretion, while HCO3--free media revealed a net absorption of oxalate (19.3 +/- 4.2 pmol cm-2 h-1) and stimulated NaCl absorption. Mucosal amiloride and dimethylamiloride (1 mM) significantly reduced the unidirectional fluxes of oxalate and enhanced sodium secretion by decreasing J(ms)Na. The anion exchange inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS; 0.1 mM, both sides) reduced the unidirectional fluxes of oxalate and chloride. Serosal epinephrine (50 muM) stimulated oxalate absorption (21.3 +/- 6.3 pmol cm-2 h-1) and sodium absorption (5.71 +/- 1.20 muequiv cm-2 h-1), whereas dibutyryl-cAMP enhanced oxalate secretion (-43.4 +/- 6.9 pmol cm-2 h-1) and stimulated chloride secretion (-7.27 +/- 0.64 muequiv cm-2 h-1). These results indicate that the P2 segment of the proximal colon possesses (a) secretory as well as absorptive capacities, (b) oxalate fluxes that are mediated by pathways involving Na+, Cl-, HCO3- transport and (c) a net oxalate flux that is sensitive to absorptive and secretory stimuli.
引用
收藏
页码:206 / 212
页数:7
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