Wiederholt M, Zadunaisky J A
Pflugers Arch. 1986;407 Suppl 2:S112-5. doi: 10.1007/BF00584939.
We have found that membrane potential in the isolated ciliary epithelium of the shark, Squalus acanthias, is -53 mV. High extracellular potassium or ouabain (10(-5) mol X l-1) decrease the potential, and furosemide (10(-4) mol X l-1) hyperpolarizes it. There is no difference in membrane potential between the cells of the non-pigmented and pigmented layers. Intracellular chloride activity (64 mmol X l-1) was significantly higher than could be predicted from the equilibrium distribution (26 mmol X l-1) across the cell membranes. When furosemide was applied to the aqueous side of the epithelium, intracellular chloride activity decreased to 35 mmol X l-1 and approached electrochemical equilibrium. The data indicate that the ciliary epithelium possesses an active, furosemide-sensitive chloride transport mechanism which could be a Na-Cl or a 1 Na-1 K-2 Cl symport.
我们发现，鲨鱼（棘鲛）分离的睫状上皮中的膜电位为-53 mV。高细胞外钾或哇巴因（10^(-5) mol·L^(-1)）会降低该电位，而呋塞米（10^(-4) mol·L^(-1)）会使其超极化。非色素层和色素层细胞之间的膜电位没有差异。细胞内氯离子活性（64 mmol·L^(-1)）显著高于根据跨细胞膜的平衡分布（26 mmol·L^(-1)）所预测的值。当将呋塞米应用于上皮的水样侧时，细胞内氯离子活性降至35 mmol·L^(-1)并接近电化学平衡。数据表明，睫状上皮具有一种活跃的、对呋塞米敏感的氯离子转运机制，可能是Na-Cl或1 Na-1 K-2 Cl同向转运体。
