Basic characterization of an ouabain-resistant, bumetanide-sensitive K+ carrier-mediated transport system in J774.2 mouse macrophage-like cell line and in variants deficient in adenylate cyclase and cAMP-dependent protein kinase activities.
86Rb(K+) transport across the plasma membrane of macrophage-like cells was studied. The cells used were the wild-type J774.2 and its two variants, CT2 cells, deficient in adenylate cyclase, and J7H1 cells, deficient in cAMP-dependent protein kinase. In the three cell lines about 15% of the total 86Rb(K+) influx is transported by the K+ carrier-mediated transport system. The 86Rb(K+) efflux carried by the same transporter is negligible when measured in the absence of ouabain in the medium. Therefore this carrier conducts a net inward flux of K+ under the experimental conditions used. The transporter is sensitive to extracellular Na+ and inhibited by 'loop' diuretics; bumetanide inhibits ouabain-resistant 86Rb(K+) influx with IC50 of 0.1, 5.0, and 0.05 microM for J774.2, CT2 and J7H1 macrophages, respectively. The membrane potential of the three cells was measured, using the distribution of [3H]tetraphenylphosphonium [( 3H]TPP+) across the plasma membrane, and found to be -80.1, -108.5 and -105.1 mV for J774.2, CT2 and J7H1 cells, respectively. The addition of bumetanide to the cell medium does not alter [3H]TPP+ uptake indicating that the transporter is electrically silent. It is concluded that despite the differences in cAMP metabolism by the three macrophages, the basic characteristics of K+ carrier-mediated transport system of the three cells are very similar.
D000262:Adenylyl Cyclases / Q000172:deficiency*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002034:Bumetanide / Q000494:pharmacology*; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004232:Diuretics / Q000494:pharmacology*; D014644:Genetic Variation; D007700:Kinetics; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D009861:Onium Compounds / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism*; D011494:Protein Kinases / Q000172:deficiency*; D012413:Rubidium / Q000378:metabolism; D012964:Sodium / Q000494:pharmacology
D004232:Diuretics; D009861:Onium Compounds; D009943:Organophosphorus Compounds; D002034:Bumetanide; D010042:Ouabain; D012964:Sodium; D011494:Protein Kinases; D000262:Adenylyl Cyclases; D012413:Rubidium; D011188:Potassium; C013289:tetraphenylphosphonium