Turnheim K, Frizzell R A, Schultz S G
J Membr Biol. 1977 Oct 3;37(1):63-84. doi: 10.1007/BF01940924.
Replacement of Cl in the solutions bathing partial mucosal strips of rabbit descending colon with sulfate, isethionate, hydroxypropane-sulfonate and, to a lesser degree, ethanesulfonate stimulates active Na absorption (JNanet) when the baso-lateral pump mechanism is not saturated. These effects are rapid in onset and are readily reversible. Our findings indicate that these stimulatory anions decrease the resistance of the amiloridesensitive Na entry step at the mucosal membrane (RmNa). However, when the active Na pump mechanism at the baso-lateral membrane is saturated these stimulatory anions do not decrease the resistance of the Na entry process. These findings suggest the presence of a negative feedback between the activity of the pump mechanism and the resistance of the Na entry step which may be mediated by the size of the intracellular Na transport pool. In other words, it seems that when the baso-lateral pump is operating at its maximal rate the resistance to Na entry across the mucosal membrane through the amiloride-sensitive pathway is at a minimum and cannot be further decreased.
当兔降结肠部分黏膜条带浸泡溶液中的氯离子被硫酸根、羟乙基磺酸根、羟基丙烷磺酸根以及程度稍低的乙磺酸根取代时，在基底外侧泵机制未饱和的情况下会刺激钠的主动吸收（JNanet）。这些效应起效迅速且易于逆转。我们的研究结果表明，这些刺激性阴离子降低了黏膜膜上amiloride敏感的钠进入步骤的阻力（RmNa）。然而，当基底外侧膜上的主动钠泵机制饱和时，这些刺激性阴离子不会降低钠进入过程的阻力。这些发现提示泵机制的活性与钠进入步骤的阻力之间存在负反馈，这可能由细胞内钠转运池的大小介导。换句话说，似乎当基底外侧泵以最大速率运转时，通过amiloride敏感途径跨黏膜膜进入钠的阻力最小且无法进一步降低。
