title: Exogeneous diacylglycerols downregulate the activity of Na(+)-K+ pump in Xenopus laevis oocytes.
abstract: In this study, cell permeable diacylglycerols, sn-1,2-dioctanoglycerol (DiC8), and sn-1-oleoyl-2-acetylglycerol (OAG) were found to downregulate the activity of Na(+)-K+ pump in Xenopus laevis oocytes. Both DiC8 and OAG decreased the binding of [3H]ouabain to intact oocytes while phorbol esters did not appreciably influence the same. These diacylglycerols inhibited the amiloride-sensitive 22Na+ influx and ouabain-sensitive 86Rb+ uptake in the oocytes. Furthermore, DiC8 prevented the 22Na+ efflux from the oocytes preloaded with 22Na+. Addition of H-7 to DiC8- and OAG-treated oocytes stimulated the pump activity curtailed by the two latters. The impairment of Na(+)-K+ pump activity by diacylglycerols suggests that protein kinase C activators may stimulate endocytosis of membrane-coupled Na(+)-K+ ATPase.
authors.affiliation: Unité Fonctionnelle de Biologie Cellulaire, Faculté de Médecine, Université de Rennes, France.
authors.forename: N A
authors.initials: NA
authors.lastname: Khan
authors.forename: V
authors.initials: V
authors.lastname: Quemener
authors.forename: J P
authors.initials: JP
authors.lastname: Moulinoux
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002462:Cell Membrane / Q000201:enzymology; D004075:Diglycerides / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000494:pharmacology; D007700:Kinetics; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D012413:Rubidium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014982:Xenopus laevis
chemical_list: D004075:Diglycerides; D007546:Isoquinolines; D010879:Piperazines; C044295:1,2-dioctanoylglycerol; D000584:Amiloride; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C038237:1-oleoyl-2-acetylglycerol; D012964:Sodium; D011493:Protein Kinase C; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium; D013755:Tetradecanoylphorbol Acetate