Furosemide-sensitive K+ transport in transformed and nontransformed rat liver epithelial cells: regulation by protein kinase C and involvement in cell growth.
Using Rb+ as a K+ tracer and atomic absorption spectrophotometry for measuring the Rb+ stable isotope, we studied K+ transport systems and their regulation by protein kinase C in nontransformed and spontaneously transformed rat liver epithelial cells. Ouabain-sensitive Na+/K(+)-ATPase and the furosemide-sensitive Na+/K+/Cl- cotransport had comparable activity ratios in both cell types (0.92 and 1 in nontransformed and transformed rat liver epithelial cells, respectively). The protein kinase C activators, dioctanoylglycerol and phorbol myristate acetate, partly inhibited the Na+/K+/Cl- cotransport in both cell types but their effect was stronger in nontransformed cells, suggesting that, in transformed cells, the Na+/K+/Cl- cotransport had partly lost the ability to be inhibited by protein kinase C. In both cell types, phorbol myristate acetate had little and dioctanoylglycerol had no inhibitory effect on Na+/K(+)-ATPase. Furosemide (1 mM) partly inhibited the [3H]thymidine incorporation in both cell types, suggesting an involvement of the Na+/K+/Cl- cotransport in rat liver epithelial cell growth.
Groupe de Recherche sur les Signaux Lipidiques Membranaires, Faculté des Sciences Pharmaceutiques et Biologiques, Rennes, France.
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JP
Anger
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L
Vernhet
A
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Hichami
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Corlu
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E
Lepalabe
A
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Troussard
A
A
Legrand
D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002461:Cell Line, Transformed; D004075:Diglycerides / Q000494:pharmacology; D004232:Diuretics / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects; D005665:Furosemide / Q000494:pharmacology*; D017136:Ion Transport / Q000187:drug effects; D008099:Liver / Q000166:cytology / Q000187:drug effects*; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D011493:Protein Kinase C / Q000502:physiology*; D051381:Rats; D012413:Rubidium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism
D004075:Diglycerides; D004232:Diuretics; D004791:Enzyme Inhibitors; C044295:1,2-dioctanoylglycerol; D010042:Ouabain; D005665:Furosemide; D011493:Protein Kinase C; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium; D013755:Tetradecanoylphorbol Acetate; D011188:Potassium; D013936:Thymidine