Fura-2探针对希土Y3+跨PC12细胞膜行为研究

使用AR-MIC-CM阳离子测定系统，发展Fura-2荧光测定技术，将其应用于测定细胞内游离希土离子Y³⁺，并以此研究了Y³⁺跨PC12细胞(大鼠嗜铬细胞瘤细胞)膜的行为。结果表明：在模拟细胞内各离子组分，pH=7.05的溶液中，测得表观解离常数为4.5p mol·L^-1。对于PC12细胞，静息条件下Y³⁺不能跨越细胞膜进入胞内。与钙离子通道相关的KCl和去甲肾上腺素均不能刺激希土Y³⁺过膜。用Ouabain(哇巴因)使胞内Na⁺超载后，Y³⁺可过膜进入细胞内，且过膜量与胞外Y³⁺浓度和胞内Na⁺超载程度有一定的浓度依赖关系，提示Y³⁺可以经由Na⁺/Y³⁺交换机制过膜而进入细胞内。

RESEARCH ON TRANSMEMBRANE BEHAVIORS OF Y3+ BY Fura-2 FLUORESENT PROBE

By the use of the applied research cation measurement system, Fura-2 fluorescence measurment method was forwarded to detect the intracellular Y³⁺ concentration, and used for investigating the transmembrane behaviors of Y³⁺ to PC12 cells. An apparent dissociation constant of Y³⁺-Fura-2 was 4.5p mol·L^-1 in solutions simulating intracellular ionic composition, with pH 7.05. Y³⁺ ions could not enter PC12 cell under the normal condition, and also could not enter the cell via the calcium channel stimulated by KCl and norpinephrine. However Y³⁺ ions entered PC12 cell after Na⁺ ions within the cell were overloaded using Ouabain. Amonut of Y³⁺ entering P12 cell were related to both outer cellular Y³⁺ concentration and intracellular overloaded Na⁺ concentration. It is suggested that Y³⁺ enter the cell in Na⁺-Y³⁺ exchanging mechanism.