稀土La3+跨PC12细胞膜行为研究

使用AR-CM-M1C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稀土离子La³⁺，并以此研究了La³⁺跨PC12细胞（大鼠嗜铬细胞瘤细胞）膜的行为.结果表明：在模拟细胞内离子组分，pH=7.05的溶液中，测得La³⁺-Fura-2的表观解离常数为3.27×10^-11 mol·L^-1.对于PC12细胞，静息条件下La³⁺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稀土La³⁺过膜.用哇巴因（ouabain）使胞内Na⁺超载后，La³⁺可过膜进入细胞内，且过膜量与胞外La³⁺浓度和胞内Na⁺超载程度有一定的浓度依赖关系，提示La³⁺可以经由Na⁺／La³⁺交换机制过膜而进入细胞内.

Research on Transmembrane Behaviors of La3+ to PC12 Cells

By the use of the applied research cation measurement system, Fura-2 fluorescence measurement method was forwarded to detect the intracellular La³⁺ concentration, and used for investigating the transmembrane behaviors of La³⁺ to PC12 cells. An apparent dissociation constant of La³⁺-Fura-2 was 3.27×10^-11 mol·L^-1 in solutions simulating intracellular ionic composition, with pH 7.05. La³⁺ 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 La³⁺ entered PC12 cell after Na⁺ within the cell were overloaded using ouabain. Amount of La³⁺ entering PC12 cell were related to both outer cellular La³⁺ concentration and intracellular overloaded Na⁺ concentration. It is suggested that La³⁺ enter the cell in Na⁺/La³⁺ exchanging mechanism.