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Titolo:
P-glycoprotein phosphorylation/dephosphorylation and cellular accumulationof L-DOPA in LLC-GA5 Col300 cells
Autore:
Sampaio-Maia, B; Gomes, R; Soares-Da-Silva, P;
Indirizzi:
Fac Med Porto, Inst Pharmacol & Therapeut, P-4200 Oporto, Portugal Fac MedPorto Oporto Portugal P-4200 Therapeut, P-4200 Oporto, Portugal
Titolo Testata:
JOURNAL OF AUTONOMIC PHARMACOLOGY
fascicolo: 3, volume: 19, anno: 1999,
pagine: 173 - 179
SICI:
0144-1795(199906)19:3<173:PPACA>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
PROTEIN-KINASE-C; CYCLOSPORINE-A; MULTIDRUG-RESISTANCE; OKADAIC ACID; PHOSPHORYLATION; RAT; INHIBITORS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
19
Recensione:
Indirizzi per estratti:
Indirizzo: Soares-Da-Silva, P Fac Med Porto, Inst Pharmacol & Therapeut, P-4200 Oporto, Portugal Fac Med Porto Oporto Portugal P-4200 Oporto, Portugal
Citazione:
B. Sampaio-Maia et al., "P-glycoprotein phosphorylation/dephosphorylation and cellular accumulationof L-DOPA in LLC-GA5 Col300 cells", J AUT PHARM, 19(3), 1999, pp. 173-179

Abstract

1 The present work was aimed to study the effect of PKC activation and protein-serine/threonine phosphatase (PP1/PP2 A) inhibition on P-glycoprotein (P-gp) mediated transport of L-DOPA in LLC-GA5 Col300 cells, a renal cell line expressing the human P-glycoprotein in the apical membrane.2 L-DOPA accumulation was a time-and concentration-dependent process with the following kinetic characteristics: k(in), 57.3 +/- 1.2 pmol mg protein min(-1) min(-1); k(out), 3.3 +/- 0.1 pmol mg(-1) protein min(-1); A(max), 10.6 +/- 0.8; K-m, 198 +/- 64 mu M; V-max, 5.2 +/- 0.7 nmol mg protein(-1).3 Verapamil (25 mu M), a P-glycoprotein inhibitor, markedly increased (approximate to 40% increase) the accumulation of a non-saturating concentration of L-DOPA (2.5 mu M) at both initial rate of uptake (IRU, 6 min incubation) and at steady-state (SS, 30 min incubation).4 PKC activation with phorbol 12,13-dibutyrate (PDBu, 1, 3 and 10 nM) produced a concentration-dependent decrease in L-DOPA accumulation at SS, but not at IRU. The inactive phorbol ester, 4 alpha-phorbol 12,13-didecanoate (100 nM), produced no change in L-DOPA accumulation. The effect of PDBu was completely reverted by staurosporine (100 nM). The phosphatase inhibitor okadaic acid (100 nM) reduced by 20% the accumulation of L-DOPA at IRU, but not at SS.5 It is suggested that P-glycoprotein plays a role in regulation of intracellular availability of L-DOPA in renal epithelial cells, and phosphorylation/dephosphorylation of P-glycoprotein may be involved in the regulation ofthe transporter.

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Documento generato il 05/07/20 alle ore 10:30:26