Sodium‐potassium ATPase inhibition potentiates compound 48/80‐induced histamine secretion from mast cells

The effect of ouabain on the histamine secretion induced by compound 48/80 has been studied using rat peritoneal mast cells.Ouabain did not modify histamine release in the presence of millimolar concentrations of extracellular calcium.However, when mast cells were previously washed with a calcium‐free buffer, ouabain strongly potentiated histamine release elicited by compound 48/80.The full potentiation of mast cell secretion by ouabain required 30 min preincubation before adding compound 48/80. It was inhibited by lanthanum and EGTA.Potassium deprivation mimicked the effect of ouabain. A 30 min preincubation time without potassium was also required.Potassium concentrations below 2.7 mmincreased the effect of ouabain whereas higher potassium concentrations reversed this effect.The potentiation of compound 48/80‐induced histamine release by ouabain or potassium deprivation was not immediately reversed by washing away ouabain or by adding potassium, respectively.The data confirm that sodium‐potassium ATPase is involved, through a calcium‐dependent process, in the regulation of histamine release from mast cells.