Barros L F, Yudilevich D L, Jarvis S M, Beaumont N, Young J D, Baldwin S A
Departmento of Fisiología y Biofísica, Universidad de Chile, Santiago.
Pflugers Arch. 1995 Jan;429(3):394-9. doi: 10.1007/BF00374155.
Polyclonal antibodies raised against the human erythrocyte nucleoside transporter were used to investigate the distribution of the nucleoside transporters in the placenta. Immunoblots of brush-border membranes isolated from the human syncytiotrophoblast revealed a cross-reactive species that co-migrated with the erythrocyte nucleoside transporter as a broad band of apparent M(r) 55,000. In contrast, no labelling was detected in basal membranes containing a similar number of equilibrative nucleoside transporters as assessed by nitrobenzylthioinosine (NBMPR)-binding. The absence of cross-reactive epitopes in basal membranes and their presence in brush-border membranes was confirmed by confocal immunofluorescence microscopy. These results suggest that at least two isoforms of the NBMPR-sensitive nucleoside transporter are present in the human placenta. The lumenal surfaces of fetal capillaries, small placental vessels and umbilical vein were also strongly labelled by the antibody, a finding that suggests that the high fetal-placental adenosine uptake previously reported is due to endothelial transporters.
用人红细胞核苷转运体产生的多克隆抗体来研究核苷转运体在胎盘中的分布。从人合体滋养层分离的刷状缘膜的免疫印迹显示，有一种交叉反应性条带，与红细胞核苷转运体共同迁移，表现为一条表观分子量为55,000的宽带。相比之下，通过硝基苄硫肌苷（NBMPR）结合评估，在含有相似数量平衡核苷转运体的基底膜中未检测到标记。共聚焦免疫荧光显微镜证实了基底膜中不存在交叉反应性表位，而在刷状缘膜中存在。这些结果表明，人胎盘中至少存在两种对NBMPR敏感的核苷转运体亚型。胎儿毛细血管、胎盘小血管和脐静脉的管腔表面也被该抗体强烈标记，这一发现表明先前报道的高胎儿-胎盘腺苷摄取是由于内皮转运体所致。
