Gillingham Melanie B, Scott Bradley, Elliott Diane, Harding Cary O
Department of Pediatrics, Oregon Health and Science University, Portland, OR 97239-3098, USA.
Mol Genet Metab. 2006 Sep-Oct;89(1-2):58-63. doi: 10.1016/j.ymgme.2006.06.004. Epub 2006 Jul 27.
Exercise induced rhabdomyolysis is a complication of long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) and mitochondrial trifunctional protein (TFP) deficiency that frequently leads to exercise avoidance. Dietary therapy for most subjects includes medium-chain triglyceride (MCT) supplementation but analysis of diet records indicates that the majority of patients consume oral MCT only with breakfast and at bedtime. We hypothesized that MCT immediately prior to exercise would provide an alternative fuel source during that bout of exercise and improve exercise tolerance in children with LCHAD deficiency. Nine subjects completed two 45 min moderate intensity (60-70% predicted maximum heart rate (HR)) treadmill exercise tests. Subjects were given 4 oz of orange juice alone or orange juice and 0.5 g MCT per kg lean body mass, 20 min prior to exercise in a randomized cross-over design. ECG and respiratory gas exchange including respiratory quotient (RQ) were monitored. Blood levels of acylcarnitines, creatine kinase, lactate, and beta-hydroxybutyrate were measured prior to and immediately after exercise, and again following 20 min rest. Creatine kinase and lactate levels did not change with exercise. There was no significant difference in RQ between the two exercise tests but there was a decrease in steady-state HR following MCT supplementation. Cumulative long-chain 3-hydroxyacylcarnitines were 30% lower and beta-hydroxybutyrate was three-fold higher after the MCT-pretreated exercise test compared to the test with orange juice alone. Coordinating MCT supplementation with periods of increased activity may improve the metabolic control of children with LCHAD and TFP deficiency following exercise.
运动诱发横纹肌溶解是长链3-羟基酰基辅酶A脱氢酶（LCHAD）和线粒体三功能蛋白（TFP）缺乏的一种并发症，常导致运动回避。大多数受试者的饮食治疗包括补充中链甘油三酯（MCT），但饮食记录分析表明，大多数患者仅在早餐和睡前服用口服MCT。我们假设，运动前立即服用MCT将在该次运动期间提供替代燃料来源，并提高LCHAD缺乏症儿童的运动耐量。9名受试者完成了两次45分钟的中等强度（预测最大心率（HR）的60-70%）跑步机运动测试。在随机交叉设计中，受试者在运动前20分钟单独饮用4盎司橙汁，或饮用橙汁并按每千克瘦体重服用0.5克MCT。监测心电图和呼吸气体交换，包括呼吸商（RQ）。在运动前、运动后立即以及休息20分钟后测量酰基肉碱、肌酸激酶、乳酸和β-羟基丁酸的血液水平。肌酸激酶和乳酸水平在运动后没有变化。两次运动测试之间的RQ没有显著差异，但补充MCT后稳态心率有所下降。与单独饮用橙汁的测试相比，MCT预处理运动测试后累积长链3-羟基酰基肉碱降低了30%，β-羟基丁酸升高了三倍。将MCT补充与活动增加期相协调，可能会改善LCHAD和TFP缺乏症儿童运动后的代谢控制。
