Uptake of (3)H-1-methyl-4-phenylpyridinium ((3)H-MPP(+)) by human intestinal Caco-2 cells is regulated by phosphorylation/dephosphorylation mechanisms

• Type: Article in International Scientific Journal
• Date: 2002

Authors

Martel, F (Author) FMUP; Elisa Keating (Author) FMUP; Conceicao Calhau (Author) FCNAUP; Azevedo, I (Author) Other

Journal

Title: Biochemical Pharmacology

Vol. 63

Pages: 1565-1573

ISSN: 0006-2952

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 8 Citations

Scopus - 11 Citations

Other information

Authenticus ID: P-000-PPF

DOI: 10.1016/s0006-2952(02)00888-2

Abstract (EN): Several transmembrane transporters of organic compounds are regulated by phosphorylation/dephosphorylation mechanisms. The aim of this study was to investigate the possible regulation of the intestinal uptake of organic cations by these mechanisms. The intestinal apical uptake of 1-methyl-4-phenylpyridinium (MPP(+)) was studied by incubating Caco-2 cells at 37degrees for 5 min with 200 nM (3)H-MPP(+). Uptake of (3)H-MPP(+) by Caco-2 cells was not affected by activators of protein kinase G, and was not affected or slightly reduced (by 15-20%) by activators of protein kinase A or protein kinase C. Uptake of (3)H-MPP(+) by Caco-2 cells was reduced in a concentration-dependent manner by non-selective phosphodiesterase inhibitors (3-isobutyl-1-methylxanthine (IBMX), caffeine, teophylline). The IC(50) of IBMX was found to be 119 muM (102-138; n = 9). Uptake of (3)H-MPP(+) by Caco-2 cells was not affected by inhibition of protein tyrosine kinase, but it was concentration-dependently reduced in the presence of inhibitors of mitogen-activated protein kinase. Uptake of (3)H-MPP(+) by Caco-2 cells was strongly reduced by Ca(2+)/calmodulin-mediated pathway inhibitors, but it was not dependent on extracellular Ca. Our results suggest that the intestinal apical uptake of MPP(+) is regulated by phosphorylation/dephosphorylation mechanisms, being most probably active in the dephosphorylated state. Moreover, uptake of (3)H-MPP(+) by Caco-2 cells and by the extraneuronal monoamine transporter (EMT) are regulated in a very similar manner, suggesting an important participation of EMT in the intestinal uptake of this compound.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 9