Effect of ouabain upon diuretic-sensitive K+ transport in cultured cells. Evidence for separate modes of operation of the transporter.
(1) Unidirectional K+ (86Rb) influx and efflux were measured in subconfluent layers of MDCK renal epithelial cells and HeLa carcinoma cells. (2) In both MDCK and HeLa cells, the furosemide-inhibitable and chloride-dependent component of K+ influx/efflux was stimulated 2-fold by a 30 min incubation in 1 . 10(-3) M ouabain. (3) Measurements of net K+ loss and Na+ gain in ouabain-treated cells at 1 h failed to show any diuretic sensitive component, confirming the exchange character of the diuretic-sensitive fluxes. (4) Prolonged incubations for 2.5 h in ouabain revealed a furosemide- and anion-dependent K+ (Cl-) outward net flux uncoupled from net Na+ movement. Net K+ (Cl-) outward flux was half-maximally inhibited by 2 microM furosemide. (5) After 2.5 h ouabain treatment, the anion and cation dependence of the diuretic-sensitive K+ influx/efflux were essentially unchanged when compared to untreated controls.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002460:Cell Line; D002712:Chlorides / Q000378:metabolism; D005665:Furosemide / Q000494:pharmacology*; D006367:HeLa Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism
D002712:Chlorides; D010042:Ouabain; D005665:Furosemide; D012964:Sodium; D011188:Potassium