The effects of urinary digitalislike factor on cultured vascular smooth muscle cells

Hypertension. 1988 Jun;11(6 Pt 2):645-50. doi: 10.1161/01.hyp.11.6.645.

Abstract

We attempted to purify a digitalislike factor from human urine. On the assumption that a natural ligand for the digitalis receptor should be searched for on the basis of the effects on intact cells, we used an inhibitory effect on the binding of [3H]ouabain to human erythrocytes to determine digitalislike activity. A highly polar [3H]ouabain displacing activity was obtained by a combination of chromatographic procedures including reverse-phase high performance liquid chromatography. Urine-derived [3H]ouabain displacing activity, a competitive inhibitor of ouabain binding to human erythrocytes, acted on human lymphocytes in a similar manner. The dose-response curve of this compound was parallel to that of ouabain. Urine-derived [3H]ouabain displacing activity significantly inhibited monensin-stimulated increase in ouabain-sensitive 86Rb uptake, a parameter of Na+,K+-adenosine triphosphatase (ATPase), by 95% (p less than 0.01) in cultured vascular smooth muscle cells (A10 cells). Furthermore, this compound enhanced net 45Ca influx by 30% (p less than 0.01) and reduced 45Ca efflux by 35% (p less than 0.01) in A10 cells. These results suggest that urine-derived [3H]ouabain displacing activity may be a regulator of Na+,K+-ATPase and a modulator of vascular tone.

MeSH terms

  • Animals
  • Blood Proteins / isolation & purification
  • Blood Proteins / pharmacology*
  • Calcium / metabolism
  • Cardenolides
  • Cells, Cultured
  • Digoxin*
  • Erythrocyte Membrane / metabolism
  • Humans
  • Lymphocytes / metabolism
  • Male
  • Muscle, Smooth, Vascular / cytology
  • Muscle, Smooth, Vascular / drug effects*
  • Ouabain / metabolism
  • Rats
  • Rubidium / metabolism
  • Saponins*
  • Sodium-Potassium-Exchanging ATPase / antagonists & inhibitors
  • Sodium-Potassium-Exchanging ATPase / metabolism
  • Urine / analysis*

Substances

  • Blood Proteins
  • Cardenolides
  • Saponins
  • digoxin-like factors
  • Ouabain
  • Digoxin
  • Sodium-Potassium-Exchanging ATPase
  • Rubidium
  • Calcium