Sodium transport in the hen lower intestine. induction of sodium sites in the brush border by a low sodium diet.

作者：Niels Bindslev · 发表于：The Journal of Physiology · 年份：1979 · DOI：10.1113/jphysiol.1979.sp012707 · 被引用次数：42 · 研究领域：Ion Transport and Channel Regulation、Drug Transport and Resistance Mechanisms、Amino Acid Enzymes and Metabolism

1. The fluxes of Na were measured on isolated coprodeal mucosa at 1--220 mM-Na from hens on low (L) and high (H) Na diets with the purpose of finding the location and characteristics of Na sites activated in the cellular pathway by L. 2. The influx across the brush border, JNamc, and the transmural fluxes, JNasm and JNams, were determined. Effects on these fluxes of ouabain, 10(-3) M in the serosal solution, and amiloride, 10(-4) M in the mucosal solution, were studied for both dietary states. 3. JNamc was 5--22 (L) and 0--0.8 (H) muequiv/cm2.hr at 130 mM-Na corrected for the paracellular flux of Na. The JNamc (H) is tenfold smaller than found by Choshniak, Munck & Skadhauge (1977). This discrepancy is at present inexplicable. Amiloride completely inhibited JNamc (L). Preincubation in 0 or 130 mM-Na had no effect on JNamc. Ouabain reduced JNamc (L) by only about 37% after preincubation at 130 mM-Na. The Kt of JNamc was 5.1 (L) and 50.6 (H) mM-Na. 4. JNasm was 50 (H) and 61 (L) n-equiv/cm2.hr at 6.5 mM-Na. Ouabain increased JNasm by 360% in the low Na state. The increased JNasm was inhibited 74--100% by amiloride. This is interpreted as a ouabain induced Na-Na exchange at the basolateral Na-K-ATPase and an almost complete block of JNacm by amiloride. A similar exchange of Na at the basolateral membrane in the high-Na state was revealed by 'opening' the brush border for Na with monensin added to the mucosal solution. Amiloride in itself prevented a 50% recirculation of Na via t...