L-arginine transport across the basal plasma membrane of the syncytiotrophoblast of the human placenta from normal and preeclamptic pregnancies

P. F. Speake, J. D. Glazier, P. T.Y. Ayuk, M. Reade, C. P. Sibley, S. W. D'Souza

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Abstract

Cord blood levels of nitrate/nitrite, as a measure of nitric oxide (NO), are generally increased in preeclampsia. As L-arginine is the precursor for NO synthesis, we hypothesized that L-arginine transport across the syncytiotrophoblast basal plasma membrane (BM) of placentas from preeclamptic patients is also increased. Glutamine-sensitive and -insensitive [ 3H]L-arginine uptakes into BM vesicles were measured and expressed as femtomoles per milligram of protein per minute. Total L-arginine uptake was 418 ± 15 (mean ± SEM; n = 9) in BM from control placentas (CBM) and 495 ± 27 (n = 7) in BM from preeclamptic placentas (PE BM; P < 0.05, by two-tailed t test). Glutamine insensitive (system y+) uptake was 45 ± 3 (n = 6) in CBM, with a significantly higher uptake of 97 ± 23 (n = 5) into PE BM (P < 0.05, by two-tailed t test). There was no significant difference in glutamine-sensitive uptake between the two groups. The expression of mRNA for human cationic amino acid transporter (hCAT) 1, 2, and 4 (system y+ genes) and 4F2hc (heavy chain of system y +L) was not different in homogenates of whole placenta from the two groups. Western blotting data showed that hCAT-1 protein expression in PE BM was higher than that in CBM. These data suggest increased activity of the BM system y+ cationic amino acid transporter in preeclampsia. If reflected in vivo, a similar increase in transporter activity could alter the delivery of L-arginine to syncytiotrophoblast eNOS.

Original languageEnglish
Pages (from-to)4287-4292
Number of pages6
JournalJournal of Clinical Endocrinology and Metabolism
Volume88
Issue number9
DOIs
Publication statusPublished - 1 Sep 2003

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