Greger R
Physiologisches Institut der Albert-Ludwigs-Universität, Freiburg, Hermann-Herder-Strasse 7, D-79104 Freiburg, Germany.
Pflugers Arch. 1996 Aug;432(4):579-88. doi: 10.1007/s004240050173.
Ten years ago, the basic principles operating in one specific, albeit non-mammalian, exocrine gland, the rectal gland of Squalus acanthias, were described in detail. The concept emerging from these studies appeared applicable to almost any other exocrine gland, because it involved membrane transporters which are also present in mammalian epithelial cells. Meanwhile, it has become clear that the mechanisms of NaCl secretion are diverse: the mechanisms of NaCl uptake; the ion channels involved; and also the mechanisms of hormonal control. Nevertheless, several steps in NaCl secretion still appear to be uniform: (1) several signalling pathways converge and act cooperatively, (2) one primary regulatory step is the upregulation of the luminal Cl- conductance, (3) secondarily active NaCl uptake mechanisms are upregulated, (4) increasing evidence links NaCl secretion to membrane trafficking and (5) the entire machinery seems to be primed to secure cellular homeostasis in terms of cytosolic ion concentrations. This brief review summarizes the mechanisms of control of NaCl secretion. The major issues addressed are the NaCl uptake mechanisms, the ion channels involved and the cellular mechanisms coordinating secretion. The major NaCl secreting cells discussed here will be the respiratory epithelial cells, the exocrine cells of pancreatic acini and the cells of colonic crypts.
十年前，人们详细描述了一种特定的外分泌腺（虽然不是哺乳动物的）——棘鲛直肠腺所遵循的基本原理。这些研究中出现的概念似乎适用于几乎任何其他外分泌腺，因为它涉及到在哺乳动物上皮细胞中也存在的膜转运蛋白。与此同时，很明显氯化钠分泌的机制是多样的：氯化钠摄取的机制、涉及的离子通道以及激素控制的机制。然而，氯化钠分泌的几个步骤似乎仍然是一致的：（1）几种信号通路汇聚并协同作用；（2）一个主要的调节步骤是管腔氯离子电导的上调；（3）继发性主动氯化钠摄取机制被上调；（4）越来越多的证据将氯化钠分泌与膜运输联系起来；（5）整个机制似乎是为了确保细胞溶质离子浓度方面的细胞稳态而准备的。这篇简短的综述总结了氯化钠分泌的控制机制。所讨论的主要问题是氯化钠摄取机制、涉及的离子通道以及协调分泌的细胞机制。这里讨论的主要氯化钠分泌细胞将是呼吸道上皮细胞、胰腺腺泡的外分泌细胞和结肠隐窝细胞。
