SELECTIVE DYE AND IONIC PERMEABILITY OF GAP JUNCTION CHANNELS FORMED BY CONNEXIN45

被引:150
作者
VEENSTRA, RD
WANG, HZ
BEYER, EC
BRINK, PR
机构
[1] WASHINGTON UNIV,SCH MED,DEPT MED,ST LOUIS,MO 63110
[2] WASHINGTON UNIV,SCH MED,DEPT PEDIAT,ST LOUIS,MO 63110
[3] WASHINGTON UNIV,SCH MED,DEPT CELL BIOL & PHYSIOL,ST LOUIS,MO 63110
[4] SUNY STONY BROOK,HLTH SCI CTR,DEPT PHYSIOL & BIOPHYS,STONY BROOK,NY 11794
关键词
2'; 7'-DICHLOROFLUORESCEIN; SUBCONDUCTANCE STATE; 6-CARBOXYFLUORESCEIN; CHANNEL CONDUCTANCE RATIO; PERMEABILITY;
D O I
10.1161/01.RES.75.3.483
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
Gap junctions are thought to mediate the direct intercellular coupling of adjacent cells by the gating of an aqueous pore permeable to ions and molecules of up to 1 kD or 8 to 14 Angstrom in diameter. We performed ion-substitution and dye-transfer experiments to determine the relative Cl-/K+ conductance and dye permeability of anionic fluorescein derivatives in chick connexin45 (Cx45) channels. We demonstrate that Cx45 forms a 26+/-6-picosiemen (pS) channel with a maximum detectable Cl- permeability of 0.2 relative to K+ or Cs+. Although homogeneous channel conductances were observed in multichannel recordings, the open probability estimates were indicative of nonhomogeneous gating behavior and occasional cooperativity. A second conductance state of 19+/-4 pS begins to predominate at higher voltages. Cx45 gap junctions are permeable to 2',7'-dichlorofluorescein but are not permeable to the more polar 6-carboxyfluorescein dye. These observations suggest that the Cx45 pore diameter is approximate to 10 Angstrom and is associated with a fixed negative charge within the junctional channel.
引用
收藏
页码:483 / 490
页数:8
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