Armstrong J W, Cragoe E J, Bourke J R, Huxham G J, Manley S W
Department of Physiology and Pharmacology, University of Queensland, Brisbane, Australia.
Mol Cell Endocrinol. 1992 Oct;88(1-3):105-10. doi: 10.1016/0303-7207(92)90014-w.
The thyroid epithelium transports fluid bidirectionally using active transport of Na+ ions from apical to basal poles and active transport of Cl- in the reverse direction. In these studies we sought evidence for cyclic AMP activated Cl- channels on the apical membranes of thyroid cells in monolayer culture. A Cl(-)-dependent basal-positive short-circuit current (ISC) was demonstrated in bicameral chambers after blocking Na+ transport with phenamil, and responded to prostaglandin (PG) E2 with a spike of 5-10 min duration followed by a plateau. The onset of the spike coincided with an increase in the conductance of the epithelium. Application of an external Cl- concentration gradient, by replacing the medium in the apical compartment with Cl(-)-free medium, resulted in an increase in ISC after, but not before, addition of PGE2. Forskolin and thyroid-stimulating hormone (TSH), but not A23187, also stimulated Cl- transport. In conjunction with previous observations that Cl- transport was mediated by a bumetanide-sensitive NaKCl2 symporter on the basal membrane, these observations indicated the presence of a cyclic AMP activated Cl- conductance in the apical membrane of thyroid cells.
甲状腺上皮细胞通过钠离子从顶端向基底极的主动转运以及氯离子反向的主动转运来双向运输液体。在这些研究中，我们寻找单层培养的甲状腺细胞顶端膜上存在环磷酸腺苷激活的氯离子通道的证据。在用苯那普利阻断钠离子转运后，在双室小室中证明了一种依赖氯离子的基础正向短路电流（ISC），并且对前列腺素（PG）E2有反应，先是持续5 - 10分钟的峰值，随后是平台期。峰值的开始与上皮细胞电导的增加同时发生。通过用无氯培养基替换顶端隔室中的培养基来施加外部氯离子浓度梯度，在添加PGE2之后而非之前导致ISC增加。福斯高林和促甲状腺激素（TSH），但不是A23187，也刺激氯离子转运。结合先前的观察结果，即氯离子转运由基底膜上对布美他尼敏感的NaKCl2协同转运体介导，这些观察结果表明甲状腺细胞顶端膜中存在环磷酸腺苷激活的氯离子电导。
