The mechanism of histamine release induced by the ionophore X537A from isolated rat mast cells. I. Significance of monovalent cations, calcium, metabolic energy and temperature.

Histamine release induced by X537A from isolated rat mast cells was dependent on the presence of sodium or potassium but not on calcium in the incubation medium. The rate of release was faster in potassium than in sodium, but the final release was the same after prolonged incubation. Extracellular calcium as well as metabolic inhibitors depressed the rate or release induced by X537A. Pretreatment of mast cells with either EDTA or the ionophore A23187 in the absence of extracellular calcium did not influence subsequent release induced by X537A. The findings of release at 45 degrees C and lack of release at 0 degrees C distinguish the mechanism of action of X537A from calcium- energy-dependent releasing agents like compound 48/80 and A23187 on the one hand and the simple lytic action of decylamine on the other.