Cotton K D, Hollywood M A, Thornbury K D, McHale N G
School of Biomedical Science, The Queen's University of Belfast, Northern Ireland, United Kingdom.
Am J Physiol. 1996 Mar;270(3 Pt 1):C969-73. doi: 10.1152/ajpcell.1996.270.3.C969.
Freshly dispersed cells from sheep urinary bladder were voltage clamped using the whole cell and inside-out patch-clamp technique. Cibacron and Basilen blue increased outward current in a dose-dependent manner with a half-maximal response at 10(-5)M. Suramin, in concentrations to 10(-3)M, had no such effect. The Cibacron blue response was abolished in Ca2+ -free physiological salt solution, suggesting that it was acting on a Ca2+ -dependent current. Similarly, the Cibacron blue-sensitive current was significantly attenuated by charybdotoxin. Cibacron blue did not modulate inward current nor were its effects modified by caffeine or heparin, suggesting that its effect on outward current was not secondary to an increase in intracellular Ca2+. Application of 10(-4)M Cibacron blue to the inside membrane of excised patches caused a rapid increase in open probability of a large conductance (300 pS) K+ channel. These results suggest that Cibacron blue is a potent activator of a Ca2+ -dependent outward current in bladder smooth muscle cells in addition to its action as a purinergic blocker.
使用全细胞和内向外膜片钳技术对从绵羊膀胱新鲜分离的细胞进行电压钳制。汽巴克隆蓝和碱性蓝以剂量依赖方式增加外向电流，在10^(-5)M时出现半数最大反应。浓度达10^(-3)M的苏拉明没有这种作用。在无Ca2+的生理盐溶液中，汽巴克隆蓝的反应消失，表明它作用于一种Ca2+依赖性电流。同样，汽巴克隆蓝敏感电流被蝎毒素显著减弱。汽巴克隆蓝不调节内向电流，其作用也不受咖啡因或肝素影响，这表明它对外向电流的作用并非继发于细胞内Ca2+的增加。将10^(-4)M汽巴克隆蓝应用于切除膜片的内膜，可使一种大电导（300 pS）钾通道的开放概率迅速增加。这些结果表明，除了作为嘌呤能阻滞剂的作用外，汽巴克隆蓝还是膀胱平滑肌细胞中Ca2+依赖性外向电流的有效激活剂。
