L-3,4-dihydroxyphenylalanine and L-5-hydroxytryptophan share the same transporter in Opossum kidney cells

• Type: Article in International Scientific Journal
• Date: 1998

Authors

gomes, p (Author) Other; serrao, mp (Author) Other; vieira-coelho, ma (Author) Other; soares-da-silva, p (Author) FMUP

Journal

Title: International Journal of Biochemistry and Cell Biology

Vol. 30

Pages: 243-250

ISSN: 1357-2725

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 4 Citations

Scopus - 0 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Authenticus ID: P-001-8K2

DOI: 10.1016/s1357-2725(97)00115-5

Abstract (EN): Opossum kidney (OK) cells, which have the ability to synthesise dopamine and 5-HT, have been used as an in vitro model for the study of renal actions of dopamine and 5-hydroxytryptamine (5-HT). The present study reports on the uptake of their immediate precursors L-3,4-dihydroxyphenylalanine (L-DOPA) and L-5-hydroxytryptophan (L-5-HTP). IC(50) values for L-5-HTP (1569 mu M) obtained in the presence of a nearly saturating (250 mu M) concentration of L-DOPA were 6-fold those obtained when using non-saturating (0.25 and 25 mu M) concentrations of L-DOPA (251 and 266). V(max) values (in nmol mg protein(-1) 6 min(-1)) for L-DOPA uptake are identical in the absence (13.6) and the presence of 250 mu M L-5-HTP (13.3), but K(m), values (mu M) are significantly greater (P < 0.05) when L-DOPA uptake was studied in the presence of L-5-HTP (90 vs 179). IC(50) values for L-DOPA (679 mu M) obtained in the presence of a near saturating (250 mu M) concentration of L-5-HTP were almost 3-fold those obtained when nonsaturating (0.25 and 25 mu M) concentrations of L-5-HTP were used (254 and 220). V(max) values (in nmol mg protein(-1) 6 min(-1)) for L-5-HTP uptake are identical in the absence (11.2) and the presence of 250 mu M L-DOPA (11.7), but K(m) values (mu M) are significantly greater (P < 0.05) when L-5-HTP uptake was studied in the presence of L-DOPA (103 vs 220). It is concluded that L-DOPA and L-5-HTP share the same transporter(s) and each compound exerts a competitive type of inhibition upon the other.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8