Dopamine-induced inhibition of Na+-K+-ATPase activity requires integrity of actin cytoskeleton in opossum kidney cells

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

Authors

Pedro Gomes (Author) Other; soares-da-silva, p (Author) FMUP

Journal

Title: Acta Physiologica Scandinavica

Vol. 175 No. 2

Pages: 93-101

ISSN: 0001-6772

Publisher: Blackwell

Indexing

ISI Web of Knowledge - 14 Citations

Scopus - 14 Citations

Other information

Authenticus ID: P-00H-KAK

DOI: 10.1046/j.1365-201x.2002.00972.x

Abstract (EN): The present study evaluated the importance of the association between Na+ -K+ -ATPase and the actin cytoskeleton on dopamine-induced inhibition of Na+ -K+ -ATPase activity. The approach used measures the transepithelial transport of Na+ in monolayers of opossum kidney (OK) cells, when the Na+ delivered to Na+ -K+ -ATPase was increased at the saturating level by amphotericin B. The maximal amphotericin B (1.0 mu g mL(-1) ) induced increase in short-circuit current (I-sc ) was prevented by ouabain (100 mu M) or removal of apical Na+ . Dopamine (1 mu M) applied from the apical side significantly decreased (29 +/- 5% reduction) the amphotericin B-induced increase in I-sc , this being prevented by the D-1 -like receptor antagonist SKF 83566 (1 mu M) and the protein kinase C (PKC) inhibitor chelerythrine (1 mu M). Exposure of OK cells to cytochalasin B (1 mu M) or cytochalasin D (1 mu M), inhibitors of actin polymerization, from both cell sides reduced by 31 +/- 4% and 36 +/- 3% the amphotericin B-induced increase in I-sc and abolished the inhibitory effect of apical dopamine (1 mu M), but not that of the PKC activator phorbol-12,13-dibutyrate (PDBu; 100 nM). Colchicine (1 mu M) failed to alter the inhibitory effects of dopamine. The relationship between Na+ -K+ -ATPase and the concentration of extracellular Na+ showed a Michaelis-Menten constant (K-m ) of 44.1 +/- 13.7 mM and a V (max) of 49.6 +/- 4.8 mu A cm(-2) in control monolayers. In the presence of apical dopamine (1 mu M) or cytochalasin B (1 mu M) V (max) values were significantly (P < 0.05) reduced without changes in K (m) values. These results are the first, obtained in live cells, showing that the PKC-dependent inhibition of Na+ -K+ -ATPase activity by dopamine requires the integrity of the association between actin cytoskeleton and Na+ -K+ -ATPase.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 9