Labrecque G F, Holowka D, Baird B
Department of Chemistry, Cornell University, Ithaca, NY 14853.
J Immunol. 1989 Jan 1;142(1):236-43.
We have studied Ag-induced membrane potential changes of rat basophilic leukemia cells by using the potential-sensitive dye, bis-(1,3-diethylthiobarbiturate)trimethineoxonol. A rapid membrane depolarization is triggered by a multivalent Ag, and it has a bell-shaped dose dependence that parallels the degranulation response but not the extent of cross-linking of the IgE-receptor complexes. As the temperature is reduced from 37 degrees C, this depolarization response slows and decreases in magnitude until complete inhibition is observed at 15 degrees C, similar to the temperature dependence previously observed for the Ag-stimulated rise in cytoplasmic Ca2+ and for degranulation. The results imply that a highly temperature-dependent step subsequent to Ag binding and cross-linking is necessary for the depolarization response. A partial return to the resting potential is seen to follow the depolarization response to Ag. This repolarization process is inhibited by quinidine.HCl and Ba2+ in parallel with an inhibition of the degranulation response. Repolarization is not affected by 4-aminopyridine or by the absence of K+ in the external buffer. These data suggest that the repolarization is caused by a previously uncharacterized K+ channel.
我们使用电位敏感染料双（1,3 - 二乙基硫代巴比妥酸）三甲川氧杂羰花青研究了银诱导的大鼠嗜碱性白血病细胞膜电位变化。多价银引发快速的膜去极化，其具有钟形剂量依赖性，这与脱颗粒反应平行，但与IgE受体复合物的交联程度无关。随着温度从37℃降低，这种去极化反应变慢且幅度减小，直至在15℃时完全被抑制，这与先前观察到的银刺激的细胞质Ca2 +升高和脱颗粒的温度依赖性相似。结果表明，银结合和交联后高度依赖温度的步骤对于去极化反应是必需的。对银的去极化反应之后可观察到部分恢复到静息电位。这种复极化过程被盐酸奎尼丁和Ba2 +抑制，同时脱颗粒反应也受到抑制。复极化不受4 - 氨基吡啶或外部缓冲液中无钾的影响。这些数据表明复极化是由一种以前未被表征的钾通道引起的。
