Williams K Keven, Watsky Mitchell A
Department of Physiology, College of Medicine, University of Tennessee, Memphis, TN, USA.
Curr Eye Res. 2004 Feb;28(2):109-20. doi: 10.1076/ceyr.28.2.109.26234.
Examine the mechanism of bicarbonate maintenance of cell-to-cell coupling in rabbit corneal epithelium and endothelium.
Carboxyfluorescein was microinjected into rabbit corneal epithelial and endothelial cells. Adjacent cells were observed for fluorescence. Bathing solutions were buffered with bicarbonate, HEPES, phosphate, or acetate-citrate. The influence of intracellular pH and transmembrane voltage (V m ) were examined.
Bicarbonate was the only buffer to increase dye coupling. Substitution of bicarbonate structural analogs bisulfite and carbamate in a HEPES-buffered solution increased dye coupling in both cell types. Intracellular pH and V m alterations in corneal epithelial cells bathed in HEPES vs. bicarbonate buffered media had no significant effects on dye coupling.
Bicarbonate increases intercellular communication in the corneal epithelium and endothelium. This effect appears to result from an interaction of the bicarbonate molecule (or one of its structural analogs) with either gap junction proteins or an intermediary. We also demonstrate the presence of Cx43 in the rabbit corneal endothelium.
研究碳酸氢盐维持兔角膜上皮细胞和内皮细胞间耦合的机制。
将羧基荧光素显微注射到兔角膜上皮细胞和内皮细胞中。观察相邻细胞的荧光情况。用碳酸氢盐、羟乙基哌嗪乙磺酸（HEPES）、磷酸盐或乙酸 - 柠檬酸盐缓冲浴液。检测细胞内pH值和跨膜电压（Vm）的影响。
碳酸氢盐是唯一能增加染料耦合的缓冲剂。在HEPES缓冲溶液中用碳酸氢盐结构类似物亚硫酸氢盐和氨基甲酸盐替代，可增加两种细胞类型中的染料耦合。在HEPES缓冲培养基与碳酸氢盐缓冲培养基中培养的角膜上皮细胞，其细胞内pH值和Vm改变对染料耦合无显著影响。
碳酸氢盐可增加角膜上皮细胞和内皮细胞间的细胞通讯。这种效应似乎是由于碳酸氢盐分子（或其结构类似物之一）与间隙连接蛋白或中间介质相互作用所致。我们还证明了兔角膜内皮细胞中存在Cx43。
