PMID- 9655880
OWN - NLM
STAT- MEDLINE
DCOM- 19980803
LR  - 20131121
IS  - 0022-3565 (Print)
IS  - 0022-3565 (Linking)
VI  - 286
IP  - 1
DP  - 1998 Jul
TI  - Functional characterization of an organic cation transporter (hOCT1) in a 
      transiently transfected human cell line (HeLa).
PG  - 354-61
AB  - Recently, a polyspecific organic cation transporter, hOCT1, was cloned from human 
      liver. To date, limited studies examining the functional characteristics of the 
      transporter have been performed. The purpose of the present study was to develop 
      a mammalian expression system for hOCT1 and to characterize the interactions of 
      various compounds with the cloned transporter. Lipofection was used to 
      transiently transfect the hOCT1 plasmid DNA in a human cell line, HeLa. We tested 
      the interaction of an array of organic cations and other compounds with hOCT1 by 
      determining Ki values in inhibiting 14C-tetraethylammonium (TEA) transport in the 
      transfected cells. Transient expression of hOCT1 activity was observed between 24 
      and 72 hr post-transfection, with maximal expression at approximately 40 hr. TEA 
      transport was temperature dependent and saturable with Vmax and K(m) values of 
      2.89 +/- 0.448 nmol/mg protein/30 min and 229 +/- 78.4 microM, respectively. 
      14C-TEA uptake in hOCT1 plasmid DNA-transfected HeLa cells was trans-stimulated 
      by unlabeled TEA and 1-methyl-4-phenyl-pyridinium. Organic cations, including 
      clonidine, quinine, quinidine and verapamil (0.1 mM), significantly inhibited 
      14C-TEA uptake, whereas the organic anion, p-aminohippuric acid (5 mM), did not. 
      The neutral compounds, corticosterone (Ki, 7.0 microM) and midazolam (Ki, 3.7 
      microM) potently inhibited 14C-TEA uptake. The Ki values of several compounds in 
      interacting with hOCT1 differed substantially from the corresponding values for 
      the rat organic cation transporter, rOCT1, and the human kidney-specific organic 
      cation transporter, hOCT2, determined in previous studies. Transiently 
      transfected HeLa cells represent a useful tool in studying the interactions and 
      kinetics of organic cations and other xenobiotics with hOCT1 and in understanding 
      the molecular events involved in organic cation transport.
FAU - Zhang, L
AU  - Zhang L
AD  - Department of Biopharmaceutical Sciences, University of California, San 
      Francisco, USA.
FAU - Schaner, M E
AU  - Schaner ME
FAU - Giacomini, K M
AU  - Giacomini KM
LA  - eng
GR  - GM-36780/GM/NIGMS NIH HHS/United States
GR  - GM-57656/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - J Pharmacol Exp Ther
JT  - The Journal of pharmacology and experimental therapeutics
JID - 0376362
RN  - 0 (Carrier Proteins)
RN  - 0 (Membrane Proteins)
RN  - 0 (Organic Cation Transporter 1)
RN  - 0 (Recombinant Proteins)
RN  - 0 (Tetraethylammonium Compounds)
RN  - R60L0SM5BC (Midazolam)
RN  - W980KJ009P (Corticosterone)
SB  - IM
MH  - Carrier Proteins/*physiology
MH  - Corticosterone/pharmacology
MH  - HeLa Cells
MH  - Humans
MH  - Membrane Proteins/*physiology
MH  - Midazolam/pharmacology
MH  - Organic Cation Transporter 1
MH  - Permeability
MH  - Recombinant Proteins
MH  - Structure-Activity Relationship
MH  - Tetraethylammonium Compounds/pharmacokinetics
MH  - Transfection
EDAT- 1998/07/10 00:00
MHDA- 1998/07/10 00:01
CRDT- 1998/07/10 00:00
PHST- 1998/07/10 00:00 [pubmed]
PHST- 1998/07/10 00:01 [medline]
PHST- 1998/07/10 00:00 [entrez]
PST - ppublish
SO  - J Pharmacol Exp Ther. 1998 Jul;286(1):354-61.