Burch H B, Choi S, Dence C N, Alvey T R, Cole B R, Lowry O H
J Biol Chem. 1980 Sep 10;255(17):8239-44.
Rats were given large parenteral loads of fructose and the different segments of single nephrons then analyzed for fructose metabolites, fructose metabolizing enzymes, and nucleotide high energy phosphates. Fructokinase and fructose-1-P aldolase activities, and all the major metabolite and nucleotide effects, were confined to the proximal tubule. The proximal straight segment had the highest fructokinase and suffered the greatest changes. In this segment, fructose-1-P rose to 60 mmol/kg (dry weight basis) and glycerol-3-P and glucose-6-P reached 8 and 12 mmol/kg, respectively. ATP fell 80% and GTP (judging from the changes in GTP plus GDP) fell by the same percentage, but UTP was less affected. Total adenylate decreased 50%. In the proximal convoluted tubule, where fructokinase was lower and fructose-1-P aldolase higher than in the straight segment, fructose-1-P rose ony one-fourth as much and glucose-6-P was almost unchanged. In contrast, glycerol-3-P rose more, reaching 16 mmol/kg. Other substances measured along the nephron were glycerol-3-P dehydrogenase, fructose-1,6-bisphosphate aldolase, fructose, glucose, fructose bisphosphate, triose phosphate, and 6-P-gluconate. Control ATP levels were found to be highest in the distal tubule.
给大鼠静脉注射大量果糖，然后分析单个肾单位的不同节段中的果糖代谢产物、果糖代谢酶和核苷酸高能磷酸化合物。果糖激酶和果糖-1-磷酸醛缩酶的活性，以及所有主要代谢产物和核苷酸的效应，都局限于近端小管。近端直段的果糖激酶活性最高，变化也最大。在该节段中，果糖-1-磷酸升至60 mmol/kg（以干重计），甘油-3-磷酸和葡萄糖-6-磷酸分别达到8 mmol/kg和12 mmol/kg。ATP下降了80%，GTP（根据GTP加GDP的变化判断）下降了相同的百分比，但UTP受影响较小。总腺苷酸减少了50%。在近端曲管中，果糖激酶活性低于直段，果糖-1-磷酸醛缩酶活性高于直段，果糖-1-磷酸仅升高了四分之一，葡萄糖-6-磷酸几乎没有变化。相比之下，甘油-3-磷酸升高得更多，达到16 mmol/kg。沿肾单位测量的其他物质有甘油-3-磷酸脱氢酶、果糖-1,6-二磷酸醛缩酶、果糖、葡萄糖、果糖二磷酸、磷酸丙糖和6-磷酸葡萄糖酸。发现远端小管中的对照ATP水平最高。
