title: Fibroblast growth factor induces a transient net K+ influx carried by the bumetanide-sensitive transporter in quiescent BALB/c 3T3 fibroblasts.
abstract: The bumetanide-sensitive transport system performed a net efflux of K+ in serum deprived quiescent cells. The addition of partially purified fibroblast growth factor (FGF) to G0/G1 phase 3T3 fibroblasts induced a transient net influx of K+, carried out by the bumetanide-sensitive transport system for 2-6 minutes. The stimulation of the bumetanide-sensitive K+ influx by FGF was followed by stimulation of the ouabain-sensitive K+ influx. In addition, both the bumetanide-sensitive and the ouabain-sensitive K+ influxes were found to be similarly stimulated when the G0/G1 3T3 cells were treated with insulin. These results suggest that growth factors such as FGF and insulin induce a change in the action of the bumetanide-sensitive transporter from performing net K+ efflux along its concentration gradient to an uphill transport pumping of K+ into the cell. We propose, therefore, that the bumetanide-sensitive transporter contributes to the increase in the intracellular K+ (and probable Na+) stimulated by growth factors such as FGF and insulin in early G1 phase of the cell cycle.
mesh_terms: D000818:Animals; D002034:Bumetanide / Q000494:pharmacology*; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002453:Cell Cycle; D002460:Cell Line; D004232:Diuretics / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005346:Fibroblast Growth Factors / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D051379:Mice; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D012413:Rubidium / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D004232:Diuretics; D007328:Insulin; D002034:Bumetanide; D010042:Ouabain; D005346:Fibroblast Growth Factors; D012413:Rubidium; D011188:Potassium