Urea transporters are distributed in endothelial cells and mediate inhibition of L-arginine transport

Laszlo Wagner, Janet D. Klein, Jeff M. Sands, Chris Baylis

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Abstract

Our laboratory previously reported that uremic levels of urea inhibit L-arginine (L-Arg) transport into endothelial cells. The present study further investigated this effect. We measured L-Arg transport in cultured bovine aortic endothelial cells with normal or high urea (25 mM). The urea transport inhibitor phloretin abolished the inhibitory effect of urea on L-Arg transport, suggesting a role for urea transporters (UTs). We screened bovine aortic endothelial cells and several other endothelial cell types for the presence of UTs by using Western blot analysis. UT-B was present in all endothelial cells, irrespective of species or location of derivation, whereas UT-A distribution was variable and sparse. UT-B was also abundant in rat aorta, mesenteric blood vessels, and spinotrapezius muscle, whereas UT-A distribution was, again, variable and sparse. Chronic elevation of urea had variable, inconsistent effects on UT abundance. This study showed that urea must enter endothelial cells, probably by UT-B, to inhibit L-Arg transport. In view of the wide distribution of UT-B in rat vasculature, elevated blood urea nitrogen may lead to endothelial L-Arg deficiency in vivo.

Original languageEnglish
Pages (from-to)F578-F582
JournalAmerican Journal of Physiology - Renal Physiology
Volume283
Issue number3 52-3
Publication statusPublished - Sep 1 2002

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Keywords

  • Blood vessels
  • Nitric oxide
  • Phloretin
  • Uremia

ASJC Scopus subject areas

  • Physiology
  • Urology

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