Regan J J, Doorneweerd D D, Gilboe D P, Nuttall F Q
Metabolism. 1980 Oct;29(10):965-9. doi: 10.1016/0026-0495(80)90040-2.
Fructose and glucose, when administered as a single, large intravenous dose (500 mg/kg) produced opposite effects on key regulatory enzymes of glycogen metabolism in intact normal fed animals. Glucose rapidly stimulated glycogen synthase phosphatase activity and increased the proportion of glycogen synthase in the active (I) form as expected; fructose reduced synthase phosphatase activity and the proportion of synthase in the I form. Glucose also stimulated a reduction in the proportion of phosphorylase in the active (a) form, whereas fructose stimulated an increase in the proportion of phosphorylase in thea form. The effect of fructose was not mediated by an increase in cyclic adenylate (cAMP) concentration nor by a conversion of phosphorylase kinase b to phosphorylase kinase a. As expected, the concentration of ATP decreased significantly. The increase in proportion of phosphorylase in the a form may be due to stimulation of phosphorylase kinase b activity by a decrease in the intracellular ATP:Mg++ ratio or by increase in intracellular Ca++ concentration. The mechanism of the fructose-induced change in synthase phosphatase activity and in synthase I activity is unknown.
在正常进食的完整动物中，当以单次大剂量静脉注射（500毫克/千克）给予果糖和葡萄糖时，它们对糖原代谢的关键调节酶产生了相反的作用。正如预期的那样，葡萄糖迅速刺激糖原合酶磷酸酶活性，并增加活性（I）形式的糖原合酶比例；果糖则降低合酶磷酸酶活性以及I形式合酶的比例。葡萄糖还促使活性（a）形式的磷酸化酶比例降低，而果糖则促使a形式的磷酸化酶比例增加。果糖的作用并非由环腺苷酸（cAMP）浓度的增加介导，也不是由磷酸化酶激酶b向磷酸化酶激酶a的转化介导。正如预期的那样，ATP浓度显著降低。a形式的磷酸化酶比例增加可能是由于细胞内ATP:Mg++比例降低或细胞内Ca++浓度增加刺激了磷酸化酶激酶b的活性。果糖诱导合酶磷酸酶活性以及合酶I活性变化的机制尚不清楚。
