Jackson M J
J Physiol. 1984 Mar;348:417-29. doi: 10.1113/jphysiol.1984.sp015117.
The effects of ion substitution and inhibitors on the transport of two representative weak electrolytes, benzoic acid and amphetamine, across short-circuited rat jejunum in vitro have been studied. The spontaneous asymmetries in the transport of the weak electrolytes were not dependent on the presence of either bicarbonate or chloride in the incubation medium. Net transport of the weak electrolytes was abolished when choline was substituted for sodium in the fluid bathing the mucosal surface of the tissue, but weak electrolyte transport was independent of the presence of sodium on the serosal side. Weak electrolyte transport was inhibited by ouabain and by orthovanadate. The effect of ouabain was abolished when potassium was substituted for sodium in the serosal fluid, and the effect of orthovanadate was potentiated in this condition. It was shown that the ability of the intestinal epithelium to discriminate between the ionized and non-ionized forms of weak electrolytes was not altered when choline was substituted for sodium in the incubation medium, indicating that the effect of sodium was associated with the driving force for weak electrolyte transport. Weak electrolyte transport was not abolished by raising the serosal potassium concentration, suggesting that the transport process was directly related with the function of the sodium pump, rather than correlated with gradients of electrical or chemical potential established as a consequence of pump activity.
研究了离子替代和抑制剂对两种代表性弱电解质苯甲酸和苯丙胺在体外短路大鼠空肠转运的影响。弱电解质转运中的自发不对称性并不依赖于孵育介质中碳酸氢盐或氯离子的存在。当用胆碱替代灌注组织黏膜表面的液体中的钠时，弱电解质的净转运被消除，但弱电解质转运与浆膜侧钠的存在无关。哇巴因和原钒酸盐可抑制弱电解质转运。当浆膜液中的钾替代钠时，哇巴因的作用被消除，而在这种情况下原钒酸盐的作用增强。结果表明，当孵育介质中的胆碱替代钠时，肠上皮区分弱电解质离子化和非离子化形式的能力并未改变，这表明钠的作用与弱电解质转运的驱动力有关。提高浆膜钾浓度并未消除弱电解质转运，这表明转运过程与钠泵的功能直接相关，而不是与因泵活动而建立的电势或化学势梯度相关。
