Hartmann H, Probst I, Jungermann K, Creutzfeldt W
Diabetes. 1987 May;36(5):551-5. doi: 10.2337/diab.36.5.551.
The inhibitory action of insulin and proinsulin on basal and glucagon-activated glycogenolysis was studied in cultured rat hepatocytes containing [14C]glycogen. Insulin or proinsulin given as sole hormones in the presence of 5 mM glucose decreased basal release of [14C]glucose from [14C]glycogen to 20%. Half-maximal effective concentration of insulin was approximately 0.15 nM and of proinsulin was approximately 5 nM. Inhibition of [14C]lactate release from [14C]glycogen required slightly higher hormone concentrations with a similar difference in potency for insulin and proinsulin. The glucagon-stimulated release of [14C]glucose was completely blocked by insulin or proinsulin with half-maximal effective concentrations of approximately 0.2 and approximately 8 nM, respectively. In contrast, release of [14C]lactate in the presence of glucagon was increased slightly by insulin and proinsulin. Basal and glucagon-activated phosphorylase activity was inhibited by approximately 50% in a dose-dependent manner by both hormones, with differences in potency similar to those for the inhibition of glycogenolysis. These data point to a direct regulatory role of insulin in the control of hepatic glycogen breakdown even when acting as sole hormone. The results do not support the notion of a preferential inhibitory potency of proinsulin on hepatic glycogenolysis.
在含有[14C]糖原的培养大鼠肝细胞中，研究了胰岛素和胰岛素原对基础糖原分解及胰高血糖素激活的糖原分解的抑制作用。在5 mM葡萄糖存在的情况下，单独给予胰岛素或胰岛素原作为激素时，[14C]糖原的基础[14C]葡萄糖释放量降至20%。胰岛素的半数最大有效浓度约为0.15 nM，胰岛素原的半数最大有效浓度约为5 nM。抑制[14C]糖原释放[14C]乳酸所需的激素浓度略高，胰岛素和胰岛素原的效力差异相似。胰岛素或胰岛素原可完全阻断胰高血糖素刺激的[14C]葡萄糖释放，其半数最大有效浓度分别约为0.2 nM和8 nM。相反，在胰高血糖素存在的情况下，胰岛素和胰岛素原会使[14C]乳酸的释放略有增加。两种激素均以剂量依赖的方式将基础和胰高血糖素激活的磷酸化酶活性抑制约50%，其效力差异与抑制糖原分解的差异相似。这些数据表明，即使作为唯一的激素，胰岛素在控制肝糖原分解中也具有直接调节作用。结果不支持胰岛素原对肝糖原分解具有优先抑制效力的观点。
