Hostettler-Allen R, Tappy L, Blum J W
Division of Nutrition Pathology, University of Berne, Switzerland.
J Nutr. 1993 Oct;123(10):1656-67. doi: 10.1093/jn/123.10.1656.
Based on studies in Fe-deficient calves demonstrating enhanced blood lactate concentrations during treadmill exercise, the hypothesis was advanced that glucose metabolism is also disturbed at rest. Insulin-dependent glucose metabolism was therefore investigated in calves fed milk replacer containing 20 or 50 mg Fe/kg. Calves receiving only 20 mg Fe/kg of milk replacer developed moderate Fe deficiency anemia and had lower average daily gain than calves fed milk replacer containing 50 mg Fe/kg, but feed intake and feed refusals did not differ between groups. In Fe-deficient calves, insulin responses to glucose, based on intravenous and oral glucose tolerance and hyperglycemic clamp tests, were normal. Using hyperglycemic and euglycemic hyperinsulinemic clamps combined with [13C6]glucose infusions, glucose utilization and tissue sensitivity to insulin were greater in Fe-deficient calves than in Fe-adequate calves. Observed reductions in growth performance may be explained by decreased activity of Fe-dependent enzymes, increased anaerobic glycolysis and lactate-glucose cycling, adaptations that are expected to be energy expensive.
基于对缺铁犊牛的研究表明，在跑步机运动期间血乳酸浓度升高，由此提出假说，即静息时葡萄糖代谢也受到干扰。因此，对喂食含铁量为20或50毫克/千克代乳品的犊牛的胰岛素依赖性葡萄糖代谢进行了研究。仅接受20毫克铁/千克代乳品的犊牛出现中度缺铁性贫血，且日平均增重低于喂食含铁量为50毫克/千克代乳品的犊牛，但两组之间的采食量和拒食量没有差异。在缺铁犊牛中，基于静脉和口服葡萄糖耐量以及高血糖钳夹试验，胰岛素对葡萄糖的反应是正常的。使用高血糖和正常血糖高胰岛素钳夹结合[13C6]葡萄糖输注，缺铁犊牛的葡萄糖利用率和组织对胰岛素的敏感性高于铁充足的犊牛。观察到的生长性能下降可能是由于铁依赖性酶活性降低、无氧糖酵解增加和乳酸-葡萄糖循环增加所致，这些适应性变化预计会消耗大量能量。
