Silva P, Solomon R J, Epstein F H
Mount Desert Island Biological Laboratory, Salsbury Cove, Maine 04672, USA.
J Exp Zool. 1997 Dec 1;279(5):504-8.
The rectal gland of Squalus acanthias secretes chloride by a mechanism that has been termed "secondary active transport" because it depends on the activity of Na-K-ATPase. As currently described, chloride enters the cell across the basolateral cell membrane via the 2 chloride: sodium: potassium cotransporter. The energy for this electroneutral uphill movement of chloride and potassium is provided by the gradient for sodium directed into the cell. Present in the basolateral cell membrane is Na-K-ATPase that maintains the gradient for sodium. A potassium conductance, present as well in the basolateral cell membrane, recirculates the potassium. Chloride exits the cell across the luminal membrane via CFTR, the chloride conductance. This mechanism is widely distributed throughout vertebrates. This report reviews the experimental observations that led to the current definition of the mechanism of chloride transport in the rectal gland.
棘鲛的直肠腺通过一种被称为“继发性主动转运”的机制分泌氯离子，因为它依赖于钠钾ATP酶的活性。按照目前的描述，氯离子通过2氯：钠：钾协同转运体穿过基底外侧细胞膜进入细胞。氯离子和钾离子这种电中性的上坡运动所需的能量由钠离子进入细胞的梯度提供。基底外侧细胞膜中存在钠钾ATP酶，它维持着钠离子的梯度。同样存在于基底外侧细胞膜中的钾离子电导使钾离子再循环。氯离子通过氯离子电导CFTR穿过管腔膜离开细胞。这种机制在整个脊椎动物中广泛分布。本报告回顾了导致目前对直肠腺氯离子转运机制定义的实验观察结果。
