Cell swelling increases a barium-inhibitable potassium conductance in the basolateral membrane of Necturus small intestine.
Cell swelling increases a barium-inhibitable potassium conductance in the basolateral membrane of Necturus small intestine.
复制标题
细胞肿胀增加了 Necturus 小肠基底外侧膜中的钡抑制钾电导。
DOI：
10.1073/pnas.81.11.3591
复制
发表时间：
1984
影响因子：
11.1
通讯作者：
Schultz,SG
中科院分区：
文献类型：
--
作者：
Lau,KR;Hudson,RL;Schultz,SG
以前的研究表明，在浸泡在蜜腺小肠粘膜表面的溶液中加入半乳糖或丙氨酸后，立即会出现跨粘膜电位差的快速去极化(Psi MC)。紧随其后的是psi MC的复极化，与之平行的是粘膜的有效阻力与基侧膜的有效阻力之比(rm/rs)的增加；后者至少部分地被证明是由于基侧膜的电导显著增加。我们现在报道以下内容。(1)12%低渗液可引起psi-MC超极化，rM/rS增大。这些作用可被代谢抑制剂和浴液中5 mM的Ba2+所阻断；事实上，在Ba2+的存在下，psi MC去极化，rM/rS降至低值。(Ii)当浆膜液中单独含有5 mM Ba2+时，加入15 mM半乳糖可使psi MC去极化，但不会引起psi MC复极化或rM/rS增加；然而，当随后从浆膜洗液中去除Ba2+时，psi MC复极化，rM/rS增加。我们得出的结论是：(I)基底侧膜正常情况下具有Ba2+可抑制的K电导，在存在代谢抑制剂的情况下，该电导似乎被降低；(Ii)在将组织暴露于低张溶液或向粘膜溶液中添加半乳糖后，该电导增加；以及(Iii)这些反应可被代谢抑制剂阻断。这些发现表明，该组织对向粘膜溶液中添加糖或氨基酸的延迟反应可能是由于这些溶质以渗透活性形式在细胞内积累而引起的细胞肿胀的结果。
Previous studies have shown that, immediately after the addition of galactose or alanine to the solution bathing the mucosal surface of Necturus small intestine, there is a rapid depolarization of the electrical potential difference across the mucosal membrane (psi mc). This is followed by a repolarization of psi mc that is paralleled by an increase in the ratio of the effective resistance of the mucosal membrane to that of the basolateral membrane (rm/rs); the latter was shown to be, at least in part, due to a marked increase in the conductance of the basolateral membrane. We now report the following. (i) Exposure of this epithelium to a 12% hypotonic solution results in a hyperpolarization of psi mc and an increase in rm/rs. These effects are blocked by metabolic inhibitors and by the presence of 5 mM Ba2+ in the bathing solution; indeed, in the presence of Ba2+, psi mc depolarizes and rm/rs decreases to low values. (ii) Addition of 15 mM galactose to the mucosal solution when the serosal solution alone contains 5 mM Ba2+ results in a depolarization of psi mc but no subsequent repolarization of psi mc or increase in rm/rs; however, psi mc repolarizes and rm/rs increases when Ba2+ is subsequently removed from the serosal bathing solution. We conclude that (i) the basolateral membrane normally possesses a Ba2+-inhibitable K conductance, which appears to be reduced in the presence of metabolic inhibitors; (ii) after exposure of the tissue to a hypotonic solution or the addition of galactose to the mucosal solution, this conductance increases; and (iii) these responses can be blocked by metabolic inhibitors. These findings suggest that the delayed response of this tissue to the addition of sugars or amino acids to the mucosal solution may be the result of cell swelling resulting from the intracellular accumulation of these solutes in osmotically active forms.