Shears S B, Kirk C J
Biochem J. 1984 Apr 15;219(2):383-9. doi: 10.1042/bj2190383.
A rapid cellular fractionation technique [the preceding paper, Shears & Kirk (1984) Biochem. J., 219, 375-382] was employed to separate a mitochondria-rich fraction from hepatocytes within seconds. Mitochondrial Ca was estimated to be no more than 41% of total cell Ca. At least half of the mitochondrial Ca was present in an energy-dependent pool; 20% of total cell Ca was accessible to EGTA within 10s. The alpha-adrenergic agonist phenylephrine stimulated glycogen phosphorylase activity by 100% within 0.5 min and induced a loss of 20% of total cell Ca after 10 min from the EGTA-inaccessible pool. However, between 0.5 and 10 min after the addition of phenylephrine to hepatocytes there was no significant change in the Ca content of the mitochondria-rich fraction. Hepatocytes that were preloaded with Ca2+ during 90 min incubation at 0-4 degrees C expelled this cation during 20 min incubation at 37 degrees C. After this time, phenylephrine failed to alter the Ca content of a mitochondria-rich fraction. It is concluded that alpha-adrenergic agonists do not mobilize Ca2+ from hepatocyte mitochondria.
采用一种快速细胞分级分离技术[前文，希尔斯和柯克（1984年），《生物化学杂志》，219卷，375 - 382页]在数秒内从肝细胞中分离出富含线粒体的部分。据估计，线粒体钙不超过细胞总钙的41%。至少一半的线粒体钙存在于能量依赖池中；在10秒内，20%的细胞总钙可被乙二醇双四乙酸（EGTA）螯合。α - 肾上腺素能激动剂去氧肾上腺素在0.5分钟内使糖原磷酸化酶活性提高了100%，并在10分钟后从EGTA不可螯合的池中诱导细胞总钙损失20%。然而，在向肝细胞中加入去氧肾上腺素后的0.5至10分钟之间，富含线粒体部分的钙含量没有显著变化。在0 - 4摄氏度下孵育90分钟预加载了钙离子的肝细胞，在37摄氏度下孵育20分钟后排出了这种阳离子。在此之后，去氧肾上腺素未能改变富含线粒体部分的钙含量。结论是，α - 肾上腺素能激动剂不会从肝细胞线粒体中动员钙离子。
