Effects of human urine-derived digitalis-like factor on cultured renal tubular epithelial cells.
We purified a polar digitalis-like factor to apparent homogeneity from human urine using inhibition of 3H-ouabain binding to intact human erythrocytes to monitor digitalis-like activity. Since endogenous digitalis-like factor may act as a natriuretic hormone, we tested the binding characteristics of this urine-derived ouabain-displacing compound to the sodium pump in intact renal epithelial cells, in order to assess its potential physiological significance. Cultured canine and porcine epithelial cell lines, MDCK and LLC-PK1, had a high sodium pump density as estimated from 3H-ouabain binding sites. Human urine-derived ouabain-displacing compound showed a dose-related inhibition of 3H-ouabain binding to both of these cells, similar to the inhibition of unlabelled ouabain. These findings indicate that the ouabain-displacing compound is capable of acting on the sodium pump in intact renal epithelial cells and may be the circulating regulator of Na+,K+-ATPase.
Goto
A
A
Second Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
Yamada
K
K
Ishii
M
M
Yoshioka
M
M
Ishiguro
T
T
Eguchi
C
C
Sugimoto
T
T
D000818:Animals; D001667:Binding, Competitive; D001798:Blood Proteins / Q000494:pharmacology* / Q000652:urine; D002298:Cardenolides; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D004077:Digoxin; D004285:Dogs; D004848:Epithelium / Q000187:drug effects; D007684:Kidney Tubules / Q000187:drug effects*; D010042:Ouabain / Q000037:antagonists & inhibitors; D012503:Saponins; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D013552:Swine
D001798:Blood Proteins; D002298:Cardenolides; D012503:Saponins; C034504:digoxin-like factors; D010042:Ouabain; D004077:Digoxin; D000254:Sodium-Potassium-Exchanging ATPase