Intracellular activities of chloride, potassium and sodium ions in rabbit corneal epithelium.
Intracellular activities of chloride, potassium and sodium ions in rabbit corneal epithelium.
复制标题
兔角膜上皮细胞内氯离子、钾离子和钠离子的活性。
DOI：
10.1016/0005-2736(83)90056-1
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
C. van Os
中科院分区：
文献类型：
--
作者：
C. Festen;J. Slegers;C. van Os
The mechanism of ion transport in the epithelium of rabbit cornea was studied by determining the intracellular ion activity of Cl−, Na+ and K+ under various conditions. Ionic activities were measured by means of microelectrodes containing liquid ion-exchangers selective for Cl−, Na+ or K+. The Cl− activity in basal cells of the epithelium in Na+ containing bathing solutions amounts to 28±2 mM (n= 11). This value is 1.9-times greater than expected on the basis of passive distribution across the tear side membrane. This finding suggests the existence of a Cl− accumulating process. Replacement of Na+ in the aqueous bathing solution by choline or tetraethylammonium results in a reversible decrease in Cl− activity to 22±1 mM (n= 11, P< 0.025). The ratio of observed and predicted Cl− activity decreased significantly from 1.9 to 1.4 (P< 0.05). The decrease in Cl− activity due to Na+ replacement was rather slow. In contrast, after readmittance of Na+ to the aqueous bathing solution, Cl− activity rose to a stable level within 30 min. These results indicate involvement of Na+ in Cl− accumulation into the basal cells of the epithelium. The K+ and Na+ activities of the basal cells of rabbit corneal epithelium in control bathing solutions were 75±4 mM (n= 13) and 24±3 mM (n= 12), respectively. The results can be summarized in the following model for Cl− transport across corneal epithelium. Cl− is accumulated in the basal cells across the aqueous side membrane, energized by a favourable Na+ gradient. Cl− will subsequently leak out across the tear side membranes. Na+ is extruded again across the aqueous side membrane of the epithelium by the (Na++ K+)-ATPase.
