Effect of insulin on glycogen synthesis and synthetase enzyme activity in the perfused rat heart.
Effect of insulin on glycogen synthesis and synthetase enzyme activity in the perfused rat heart.
复制标题
胰岛素对灌注大鼠心脏糖原合成和合成酶活性的影响。
DOI：
10.1016/0304-4165(72)90249-8
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发表时间：
1972
期刊：
影响因子：
--
通讯作者：
Å. Hjalmarson
中科院分区：
文献类型：
--
作者：
S. Adolfsson;O. Isaksson;Å. Hjalmarson
胰岛素在体内和体外刺激心脏糖原合成。在胰岛素刺激期间，预期糖原合成酶（UDP-葡萄糖：α-1，4-葡聚糖α-4-葡糖基转移酶，EC www.example.com）活化，因为该酶是糖原合成的限速酶。然而，Huijinget al.在体外没有发现这种激活，用胰岛素灌注离体大鼠心脏30分钟（F.慧静，F.O.纳托尔角Villar-Palasi和J. Larner，Biochim. Biophys. Acta，177（1969）204）。在本研究中，用和不用胰岛素灌注离体大鼠心脏2 - 60分钟。与胰岛素在灌注液中的合成酶的激活，通过增加其活性I-形式的灌注后5和10分钟，但不是在30和60分钟后观察到。糖原迅速积累，只有2分钟的胰岛素灌注后，有显着的效果。30分钟后，胰岛素没有进一步增加糖原。合成酶的I型与糖原水平呈负相关。胰岛素改变了这种关系，因此对于给定的糖原水平，I型水平较高。葡萄糖6-磷酸，被认为是合成酶的激活剂，胰岛素增加。胰岛素也增加了标记葡萄糖的掺入。磷酸化酶活性不受影响，因此，在刺激心脏糖原合成的体外胰岛素通过增加I型激活合成酶。在胰岛素存在下发现葡萄糖6-磷酸水平增加，可能会产生额外的激活作用。
Insulin stimulates glycogen synthesis in the heartin vivoandin vitro. During insulin stimulation an activation of the glycogen synthetase enzyme (UDP-glucose: α-1, 4-glucan α-4-glucosyltransferase, EC 2.4.1.11) is expected since this enzyme is rate limiting for the synthesis of glycogen. However,in vitrosuch an activation was not found by Huijinget al., who perfused isolated rat hearts with insulin for 30 min (F. Huijing, F.O. Nuttall, C. Villar-Palasi and J. Larner,Biochim. Biophys. Acta, 177 (1969) 204).In the present study isolated rat hearts were perfused for 2–60 min with and without insulin. With insulin in the perfusate an activation of the synthetase enzyme by means of an increase in its active I-form was observed after 5 and 10 min of perfusion but not after 30 and 60 min. Glycogen was rapidly accumulated and after only 2 min of perfusion with insulin there was a significant effect. After 30 min no further increase in glycogen was obtained with insulin. The I-form of the synthetase enzyme was inversely related to the glycogen level. Insulin changed this relationship so that for a given glycogen level there was a higher level of I-form. Glucose 6-phosphate, considered to be an activator of the synthetase enzyme, was increased by insulin. Incorporation of labelled glucose was also increased by insulin. Phosphorylase enzyme activity was unaffected.Thus, in stimulating cardiac glycogen synthesisin vitroinsulin activates the synthetase enzyme by increasing the I-form. An additional activation may be exerted by the increased level of glucose 6-phosphate found in presence of insulin.