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

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Abstract
1 The effect of ouabain on the histamine secretion induced by compound 48/80 has been studied using rat peritoneal mast cells. 2 Ouabain did not modify histamine release in the presence of millimolar concentrations of extracellular calcium. 3 However, when mast cells were previously washed with a calcium-free buffer, ouabain strongly potentiated histamine release elicited by compound 48/80. 4 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. 5 Potassium deprivation mimicked the effect of ouabain. A 30 min preincubation time without potassium was also required. 6 Potassium concentrations below 2.7 mm increased the effect of ouabain whereas higher potassium concentrations reversed this effect. 7 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. 8 The data confirm that sodium-potassium ATPase is involved, through a calcium-dependent process, in the regulation of histamine release from mast cells.