慢性肾衰竭患者红细胞中赖氨酸转运能力增强。

Increased lysine transport capacity in erythrocytes from patients with chronic renal failure.

Fervenza F C, Harvey C M, Hendry B M, Ellory J C

University Laboratory of Physiology, John Radcliffe Hospital, Oxford, U.K.

Clin Sci (Lond). 1989 Apr;76(4):419-22. doi: 10.1042/cs0760419.

Abstract

The initial rate of L-lysine influx into erythrocytes from 13 patients with chronic renal failure has been measured using 14C-labelled lysine. Ten patients were on maintenance haemodialysis and three had never been dialysed. The results are compared with data obtained from 12 normal individuals. 2. The rate of lysine influx into washed cells from buffered saline containing 0.02-0.5 mmol of L-lysine/l has been calculated. The results can be fitted with a model in which influx has a single saturable component obeying Michaelis-Menten kinetics, and a linear non-saturable component. 3. In uraemic erythrocytes the saturable component had a mean Vmax. of 0.762 mmol h-1 litre-1 of cells (n = 13, SEM 0.072) and a mean Km of 68.2 mumol/l (SEM 5.7). These values in normal erythrocytes were 0.566 mmol h-1 litre-1 of cells (n = 12, SEM 0.033) and 70.5 mumol/l (SEM 4.1), respectively. The mean apparent diffusion constant (KD) for the linear component of influx was 0.224 h-1 (SEM 0.039) in uraemic cells and 0.178 h-1 (SEM 0.028) in normals. 4. The 35% increase in mean Vmax seen in uraemic erythrocytes was statistically significant (P = 0.02). A similar increase in Vmax. in uraemic cells compared with controls was seen in erythrocytes which were studied in zero-trans conditions after depletion of intracellular amino acids. The mean values of Km and KD were not significantly different in uraemia. The origins of this increased membrane transport capacity for lysine in uraemia are discussed.

摘要

采用(^{14}C)标记的赖氨酸测定了13例慢性肾功能衰竭患者红细胞摄取L-赖氨酸的初始速率。其中10例患者接受维持性血液透析，3例从未接受过透析。将结果与12名正常个体的数据进行了比较。2. 计算了赖氨酸从含有0.02 - 0.5 mmol/L L-赖氨酸的缓冲盐溶液中进入洗涤后细胞的摄取速率。结果可以用一个模型来拟合，其中摄取有一个遵循米氏动力学的单一可饱和成分和一个线性不饱和成分。3. 在尿毒症红细胞中，可饱和成分的平均最大反应速度（(V_{max})）为0.762 mmol·h⁻¹·L⁻¹细胞（(n = 13)，标准误0.072），平均米氏常数（(K_m)）为68.2 μmol/L（标准误5.7）。正常红细胞中的这些值分别为0.566 mmol·h⁻¹·L⁻¹细胞（(n = 12)，标准误0.033）和70.5 μmol/L（标准误4.1）。尿毒症细胞中摄取线性成分的平均表观扩散常数（(K_D)）为0.224 h⁻¹（标准误0.039），正常细胞中为0.178 h⁻¹（标准误0.028）。4. 尿毒症红细胞中平均(V_{max})升高35%具有统计学意义（(P = 0.02)）。在细胞内氨基酸耗尽后在零转运条件下研究的红细胞中，与对照相比，尿毒症细胞中的(V_{max})也有类似升高。尿毒症时赖氨酸这种膜转运能力增加的原因进行了讨论。