Premium
Influence of extracellular glucose concentration on organic cation transport in Caco‐2 cells
Author(s) -
Faria Ana Isabel,
Monteiro Rosário,
Mateus Nuno,
Azevedo Isabel,
Calhau Conceição
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a730-a
Subject(s) - chemistry , caco 2 , glucose transporter , extracellular , organic cation transport proteins , glucose uptake , corticosterone , transporter , endocrinology , medicine , metabolism , biochemistry , cell , biology , insulin , hormone , gene
Chronic exposure to high glucose concentration alters regulation and functional activity of cellular proteins. This study aimed to examine the influence of cellular oxidative status induced by chronic glucose exposure on intestinal organic cation absorption. Uptake of 3 H‐MPP + (1‐methyl‐4‐phenylpyridinium) by control and high glucose (HG) Caco‐2 cells (5.5 and 25 mM glucose in culture media) was evaluated, as well as transport kinetics. Effect of glucose on hOCT1 (human organic cation transporter) and hEMT (human extraneuronal monoamine transporter) expression was assessed using comparative RT‐PCR. In HG cells: 3 H‐MPP + uptake was significantly decreased (0.7 ± 0.1 versus 1.2 ± 0.04 pmol/mg protein; n=6); K m was increased and hEMT expression was significantly reduced. Additionally, two inhibitors of 3 H‐MPP + uptake in Caco‐2 cells, corticosterone and clonidine, showed different effects on 3 H‐MPP + uptake in both types of cells. In HG cells, the inhibition with corticosterone (300 μM) was lower than in control cells (78 ± 2 % of control, n=6 versus 58 ± 11 % of control, n=6); clonidine (50 μM) inhibited 3 H‐MPP + uptake in control cells, but had no effect in HG cells. These results suggest that chronic exposure to high glucose concentration alters MPP + uptake in Caco‐2 cells. This is most probably due to a decrease in hEMT units and a reduction of transport affinity that may result from a different redox status.