Protein kinase C activation causes inhibition of Na/K-ATPase activity in Madin-Darby canine kidney epithelial (MDCK) cells.
To evaluate the influence of protein kinase C (PKC) activation on Na/K-ATPase activity in MDCK cells, we studied the effect of phorbol myristate acetate (PMA) and two diacylglycerol analogues, oleoylacetylglycerol and dioctanoylglycerol, on the enzyme activity. Na/K-ATPase activity was determined by cytochemistry. PMA induced a time- and dose-dependent inhibition of Na/K-ATPase activity and at 100 ng/ml decreased the enzyme activity by 55% of the initial value. These effects were mimicked by oleoylacetylglycerol and dioctanoylglycerol, and were abolished by two inhibitors of PKC, 1-(5-isoquinolinylsulphonyl)-2-methylpiperazine (H7) and sphingosine. A phorbol ester that does not activate PKC, 4 alpha-phorbol 12,13-didecanoate, did not inhibit Na/K-ATPase activity. PMA inhibition persisted in the presence of cycloheximide and actinomycin D but not in the presence of amiloride. Dopamine (10 microM) inhibition of Na/K-ATPase activity was abolished in a dose-dependent manner by sphingosine. Results suggest that in MDCK cells Na/K-ATPase is an effector protein for PKC and that dopamine inhibition of its activity may be mediated by PKC.
Shahedi
M
M
Département de Physiologie, Faculté de Médecine Necker Enfants Malades, Paris, France.
Laborde
K
K
Bussières
L
L
Dechaux
M
M
Sachs
C
C
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004075:Diglycerides / Q000494:pharmacology; D004232:Diuretics / Q000494:pharmacology; D004285:Dogs; D004298:Dopamine / Q000494:pharmacology; D004789:Enzyme Activation; D005665:Furosemide / Q000494:pharmacology; D007700:Kinetics; D011493:Protein Kinase C / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013110:Sphingosine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004075:Diglycerides; D004232:Diuretics; D011500:Protein Synthesis Inhibitors; D003609:Dactinomycin; D000584:Amiloride; D005665:Furosemide; D003513:Cycloheximide; D011493:Protein Kinase C; D000254:Sodium-Potassium-Exchanging ATPase; D013110:Sphingosine; D013755:Tetradecanoylphorbol Acetate; D004298:Dopamine