Regulation of apical transporter of L-DOPA in human intestinal Caco-2 cells

• Tipo: Artigo em Revista Científica Internacional
• Data: 2002

Autores

Sónia Fraga (Autor) Outra; Benedita Sampaio-Maia (Autor) FMDUP; Paula Serrão (Autor) FMDUP; Soares-da-Silva P (Autor) FMDUP

Revista

Título: Acta Physiologica Scandinavica

Vol. 175 Nº 2

Páginas: 103-111

ISSN: 0001-6772

Editora: Blackwell

Indexação

ISI Web of Knowledge - 10 Citações

ISI Web of Science

Scopus - 12 Citações

Pubmed / Medline

Classificação Científica

FOS: Ciências médicas e da saúde > Outras ciências médicas

Outras Informações

ID Authenticus: P-000-P2J

Abstract (EN): The present study examined the nature of the apical inward L-3,4-dihydroxyphenylalanine (L-DOPA) transporter in human intestinal epithelial Caco-2 cells, and whether protein kinases modulate the activity of this transporter. The apical inward transfer of L-DOPA was promoted through an energy-dependent and sodium-insensitive transporter (Km=33 microM; Vmax=2932 pmol/mg protein/6 min). This transporter was insensitive to N-(methylamino)-isobutyric acid, but competitively inhibited by 2-aminobicyclo(2,2,1)-heptane-2-carboxylic acid (BCH; IC50=83 microM). The organic cation inhibitor decynium 24 failed to affect the accumulation of L-DOPA, whereas the organic anion inhibitor 4,4'-diisothiocynatostilbene-2,2'-disulphonic acid (DIDS) competitively inhibited L-DOPA uptake (IC50=83 microM). However, the apical-to-basal and basal-to-apical transepithelial transport and the cell accumulation of [3H]-PAH was close to that of [14C]-sorbitol and insensitive to DIDS (300 microM). Modulators of protein kinase A (PKA) [cyclic adenosine monophosphate (cAMP), forskolin, H-89 and cholera toxin], protein kinase G (PKG) [cyclic guanosine monophosphate (GMP), zaprinast, LY 83583 and sodium nitroprusside] and protein kinase C (PKC) (phorbol 12,13-dibutirate and chelerythrine) failed to affect the accumulation of L-DOPA. The Ca2+/calmodulin inhibitors calmidazolium and trifluoperazine inhibited L-DOPA uptake (IC50s of 53 and 252 microM, respectively), but the rise of intracellular Ca2+ by A23187 (1 microM) and thapsigargin (1 microM) played no role on L-DOPA uptake. It is concluded that Caco-2 cells take up L-DOPA over the apical cell border through the sodium-independent and pH-sensitive L-type amino acid transporter.

Idioma: Inglês

Tipo (Avaliação Docente): Científica