OCT2 and MATE1 provide bidirectional agmatine transport

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Abstract

Agmatine is a biogenic amine (L-arginine metabolite) of potential relevance to several central nervous system (CNS) conditions. The identities of transporters underlying agmatine and polyamine disposition in mammalian systems are not well-defined. The SLC-family organic cation transporters (OCT) OCT1 and OCT2 and multidrug and toxin extrusion transporter-1 (MATE1) are transport systems that may be of importance for the cellular disposition of agmatine and putrescine. We investigated the transport of [3H]agmatine and [ 3H]putrescine in human embryonic kidney (HEK293) cells stably transfected with hOCT1, hOCT2, and hMATE1. Agmatine transport by hOCT1 and hOCT2 was concentration-dependent, whereas only hOCT2 demonstrated pH-dependent transport. hOCT2 exhibited a greater affinity for agmatine (K m=1.84±0.38 mM) than did hOCT1 (Km=18.73±4. 86 mM). Putrescine accumulation was pHand concentration-dependent in hOCT2-HEK cells (Km=11.29±4.26 mM) but not hOCT1- HEK cells. Agmatine accumulation, in contrast to putrescine, was significantly enhanced by hMATE1 overexpression, and was saturable (Km=240±31 μM; V max=192±10 pmol/min/mg of protein). Intracellular agmatine was also trans-stimulated (effluxed) from hMATE1-HEK cells in the presence of an inward proton-gradient. The hMATE1-mediated transport of agmatine was inhibited by polyamines, the prototypical substrates MPP+ and paraquat, as well as guanidine and arcaine, but not L-arginine. These results suggest that agmatine disposition may be influenced by hOCT2 and hMATE1, two transporters critical in the renal elimination of xenobiotic compounds.

Original languageEnglish (US)
Pages (from-to)133-142
Number of pages10
JournalMolecular pharmaceutics
Volume8
Issue number1
DOIs
StatePublished - Feb 7 2011

Keywords

  • ATE1
  • Agmatine
  • Agmatine transporter
  • Multidrug and toxin extrusion transporter
  • OCT2
  • Organic cation transporter
  • PH-dependent transport
  • Polyamine
  • Polyamine transporter

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