肾上腺素对大鼠肝脏不同制剂中糖原磷酸化酶-α的作用。

Effect of epinephrine on glycogen phosphorylase-alpha in various preparations of rat liver.

Kauffman F C, Whittaker M, Badr M Z, Thurman R G

Department of Pharmacology and Toxicology, Rutgers University, College of Pharmacy, Piscataway, NJ 08854.

Comp Biochem Physiol B. 1990;96(1):113-8. doi: 10.1016/0305-0491(90)90350-3.

Abstract

Glycogen phosphorylase-alpha, a commonly used index of cytosolic free calcium, was compared in various preparations of rat liver in the absence and presence of 0.1 microM epinephrine. 2. Total phosphorylase in isolated perfused livers and freshly-isolated hepatocytes were the same as that observed in liver in situ; however, phosphorylase-alpha was 50% higher in perfused liver and 80% higher in hepatocytes than activities measured in situ. Total phosphorylase was reduced approximately 50% in hepatocytes maintained in primary culture for 24 hr. 3. Epinephrine increased phosphorylase-alpha approximately 2-fold in livers perfused for 30 min but only about 20% in hepatocytes incubated for 30 min. After 90 min of perfusion or incubation, epinephrine increased phosphorylase-alpha nearly 4-fold in perfused livers and only 30% in isolated hepatocytes. The results suggest that amounts of free calcium and calcium-dependent coupling of adrenergic receptors to phosphorylase-alpha differ markedly between the intact liver and isolated hepatocytes.

摘要

糖原磷酸化酶α是一种常用的胞质游离钙指标，在有无0.1微摩尔肾上腺素存在的情况下，对大鼠肝脏的各种制剂进行了比较。2. 分离的灌注肝脏和新鲜分离的肝细胞中的总磷酸化酶与原位肝脏中观察到的相同；然而，灌注肝脏中的磷酸化酶α比原位测量的活性高50%，肝细胞中的磷酸化酶α比原位测量的活性高80%。在原代培养24小时的肝细胞中，总磷酸化酶减少了约50%。3. 肾上腺素使灌注30分钟的肝脏中的磷酸化酶α增加约2倍，但在孵育30分钟的肝细胞中仅增加约20%。灌注或孵育90分钟后，肾上腺素使灌注肝脏中的磷酸化酶α增加近4倍，而在分离的肝细胞中仅增加30%。结果表明，完整肝脏和分离的肝细胞之间，游离钙的量以及肾上腺素能受体与磷酸化酶α的钙依赖性偶联存在显著差异。