PROTEIN METABOLISM IN CHRONIC RENAL FAILURE PATIENTS

终末期肾病患者蛋白质代谢的研究 我们测定了8例患者的亮氨酸动力学。研究是 在(第三阶段)之前和之后执行两次(开始 维持性透析治疗。在透析前，有一项测量是 当患者酸中毒时(第I期)，另一次是在 酸中毒纠正后补充碳酸氢钠(句号 Ii)。第一阶段和第二阶段的顺序是随机的。受试者都在 三个时期都有相同的恒定饮食。亮氨酸动力学 在预置恒定输注[1-13C]亮氨酸的过程中进行测量， [1-13C]KIC或(酮基异戊酸和呼气二氧化碳浓缩) 是直接确定的。这些值被用来计算亮氨酸 进入血浆亮氨酸池和进入全身的出现率 亮氨酸库和亮氨酸氧化速率。前者代表 蛋白质降解率；蛋白质合成率间接 用质量平衡方程估算。较高的亮氨酸氧化 没有补充碳酸氢盐的比率并不是由于较高的VCO2 三个时期的总CO2产生率没有明显差异。 或者，更高比例的内生产生的二氧化碳可能是 比非酸化状态下排泄的多。最后，这些发现可能 表示在存在的情况下氨基酸氧化的真正增强 代谢性酸中毒。

To study protein metabolism in patients with end-stage renal disease, we measured leucine kinetics in 8 patients. Study was performed twice before and once after (period III)( initiation of maintenance dialysis treatment. Before dialysis, one measurement was done when the patients are acidotic (period I), and the other during sodium bicarbonate supplementation when acidosis was corrected (period II). Sequence of Periods I and II were randomized. Subjects were on identical constant diet during all three periods. Leucine kinetics was measured during primed-constant infusion of [1-13C]leucine, [1-13C]KIC or ( keto-isocaproate and expired breath CO2 enrichment were directly determined. These values were used to calculate leucine appearance rates into the plasma leucine pool and into the total body leucine pool and leucine oxidation rate. The former represents protein degradation rat; protein synthesis rate was indirectly estimated by mass balance equation. The h igher leuc ine oxidation rate without bicarbonate supplementation was not due to higher VCO2 as total CO2 production rate was not different during the three periods. Alternatively, higher proportion of endogenously produced CO2 may be excreted than in the non-acidotic state. Finally, these findings may represent a real enhancement of amino acid oxidation in the presence of metabolic acidosis.