Figueiredo Ana E, Almeida Priscilla B, Pinheiro da Costa Bartira E, D'Avila Domingos O, Poli de Figueiredo Carlos E
Programa de Pós-graduação em Medicina e Ciências da Saúde (Nefrologia), Laboratório de Nefrologia, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil.
Adv Perit Dial. 2005;21:2-4.
L-Arginine is the substrate for nitric oxide synthesis and may enter cells by the y+ and y+ L transport systems. Peritoneal membrane characteristics may depend on vascular function and the L-arginine-nitric oxide pathway. In a cross-sectional study, we evaluated erythrocyte L-arginine uptake in stable peritoneal dialysis (PD) patients with various categories of peritoneal transport function. We used 14C as a marker and N-ethyl-maleimide as an inhibitor of the y+ system to measure maximal uptake capacity (Vma in ulmol/L cell/h) and the half-saturation constant (Km in micromol/L) in erythrocytes. The sample consisted of 41 patients (mean age: 50 +/- 17 years; 5 with diabetes; 18 men). Mean dialysate-toplasma creatinine (D/P(Cr)) was 0.62 +/- 0.14. Peritoneal membrane transport was classified as high, high-average, low-average, or low in 10, 11, 11, and 9 patients, respectively. Mean y+ L Vmax, was 208 +/- 111 micromol/L cell/h, 494 +/- 893 micromol/L cell/h, 222 +/- 59 micromol/L cell/h, and 193 +/- 63 umol/L cell/h [p = 0.404, analysis of variance (ANOVA)] for the high, high-average, low-average, and low transporters respectively. Similarly, mean y+ Vmax was 963 +/- 1034 micromol/L cell/h 843 +/- 366 micromol/L cell/h, 639 +/- 254 micromol/L cell/h, and 774 +/- 378 micromol/L cell/h (p = 0.647, ANOVA). As with Vmax, the y+ L Km and y+ Km values were not significantly different between the various peritoneal transport categories. A negative correlation was observed between y+ Vmax and Kt/V (r = -0.393, p = 0.011). Erythrocyte uptake of L-arginine does not vary with peritoneal membrane transport characteristics, but maximal L-arginine uptake capacity is higher in patients with a lower Kt/V.
L-精氨酸是一氧化氮合成的底物，可通过y+和y+L转运系统进入细胞。腹膜特性可能取决于血管功能和L-精氨酸-一氧化氮途径。在一项横断面研究中，我们评估了不同腹膜转运功能类别的稳定腹膜透析（PD）患者红细胞对L-精氨酸的摄取情况。我们使用14C作为标记物，N-乙基马来酰亚胺作为y+系统的抑制剂，来测量红细胞中的最大摄取能力（Vmax，单位为μmol/L细胞/h）和半饱和常数（Km，单位为μmol/L）。样本包括41名患者（平均年龄：50±17岁；5名患有糖尿病；18名男性）。平均透析液与血浆肌酐比值（D/P(Cr)）为0.62±0.14。腹膜转运被分别归类为高、高-平均、低-平均或低的患者人数分别为10、11、11和9名。高、高-平均、低-平均和低转运者的平均y+L Vmax分别为208±111μmol/L细胞/h、494±893μmol/L细胞/h、222±59μmol/L细胞/h和193±63μmol/L细胞/h [p = 0.404，方差分析（ANOVA）]。同样，平均y+Vmax分别为963±1034μmol/L细胞/h、843±366μmol/L细胞/h、639±254μmol/L细胞/h和774±378μmol/L细胞/h（p = 0.647，ANOVA）。与Vmax一样，不同腹膜转运类别之间的y+L Km和y+Km值无显著差异。观察到y+Vmax与Kt/V之间存在负相关（r = -0.393，p = 0.011）。红细胞对L-精氨酸的摄取并不随腹膜转运特性而变化，但Kt/V较低的患者中L-精氨酸的最大摄取能力较高。
