Shi X P, Candia O A
Mount Sinai School of Medicine, New York, NY 10029-6574, USA.
Curr Eye Res. 1995 Oct;14(10):927-35. doi: 10.3109/02713689508995132.
The bulbar-palpebral conjunctiva from albino rabbits was dissected as a cylinder and cut longitudinally to convert it to a flat epithelium that was mounted as a partition between Using-type chambers, exposing 0.38 cm2 of cross-sectional area. The tissue was bathed with a modified Tyrode's solution at 37 degrees C, pH 7.5. The tear-facing side (apical) was 14.6 +/- 1.5 mV negative relative to the basolateral side. Transepithelial resistance was 1.23 +/- 0.01 K omega.cm2 and the short-circuit current (Isc) was 14.4 +/- 1.3, microA/cm2. Sixty percent of the Isc could be accounted for by a Na(+)-dependent, bumetanide-inhibitable Cl- transport directed towards the apical side. The remainder of the Isc reflected a Na+ absorptive process at the apical surface that was amiloride resistant. Evidence was obtained that a likely contributor to this activity is an electrogenic Na(+)-glucose co-carrier. The Cl-dependent Isc was stimulated by forskolin and epinephrine. Permeabilization of the apical membrane with amphotericin B evinced a current carried by a basolateral Na+:K+ pump. An effect by heptanol suggested that part of the Isc traverse the epithelium via gap junctions. Our results imply that transport processes at the conjunctiva could influence the composition of the tear film.
将白化兔的球结膜-睑结膜分离成柱状，纵向切开使其成为扁平上皮，将其作为分隔物安装在使用型小室之间，暴露0.38平方厘米的横截面积。组织在37℃、pH 7.5的改良台氏液中浸泡。泪液面向的一侧（顶端）相对于基底外侧呈14.6±1.5 mV的负电位。跨上皮电阻为1.23±0.01 KΩ·cm²，短路电流（Isc）为14.4±1.3 μA/cm²。60%的Isc可由朝向顶端侧的Na⁺依赖性、布美他尼可抑制的Cl⁻转运来解释。Isc的其余部分反映了顶端表面对amiloride耐药的Na⁺吸收过程。有证据表明，这种活性的一个可能贡献者是一种电中性的Na⁺-葡萄糖共转运体。依赖Cl⁻的Isc受到福斯可林和肾上腺素的刺激。用两性霉素B使顶端膜通透显示出由基底外侧Na⁺:K⁺泵携带的电流。庚醇的作用表明部分Isc通过缝隙连接穿过上皮。我们的结果表明结膜处的转运过程可能会影响泪膜的成分。
