Effect of phenobarbital administration on the subcellular distribution of 125-I-thyroxine in rat liver: mportance of microsomal binding.
Effect of phenobarbital administration on the subcellular distribution of 125-I-thyroxine in rat liver: mportance of microsomal binding.
复制标题
苯巴比妥给药对大鼠肝脏中 125-I-甲状腺素亚细胞分布的影响：微粒体结合的重要性。
作者：
H. L. Schwartz;G. Bernstein;J. Oppenheimer
静脉注射示踪剂35分钟后，测定~(125)I-甲状腺素在对照组和苯巴比妥刺激大鼠肝脏匀浆中的亚细胞分布。在0.25M蔗糖中的差速离心法表明，在对与捕获的血浆蛋白结合的甲状腺激素进行适当校正后，对照动物中54%的放射性与微粒体组分有关。在接受苯巴比妥治疗的动物中，微粒体组分中的放射性百分比上升到65(p>；.001)。当131I-T4在分馏前直接加入到匀浆中时，也观察到类似的分布。与组织部分相关的甲状腺激素可用血清和酸性丁醇定量提取。这些发现表明，在体外条件下，甲状腺激素在亚细胞组分中的分配是由表面结合位点之间的平衡决定的。如果体内状态符合相同的分布平衡，则90%的肝脏/血浆浓度增加…
The subcellular distribution of 125I-thyroxine was determined in homogenates of livers from control and phenobarbital-stimulated rats 35 min following intravenous injection of tracer. Differential centrifugation in 0.25M sucrose indicated that 54% of radioactivity is associated with the microsomal fraction in control animals after appropriate corrections were made for thyroxine bound to trapped plasma proteins. In phenobarbital-treated animals the percentage radioactivity in the microsomal fraction rose to 65 (p>.001). Similar distributions were observed when 131I-T4 was added directly to the homogenate prior to fractionation. Thyroxine associated with tissue fractions could be extracted quantitatively with serum and acid butanol. These findings indicate that the partition of thyroxine among subcellular fractions under in vitro conditions is determined by equilibria among surface binding sites. If the same distribution equilibria characterize the in vivo state, 90% of the increase in liver/plasma concentr...