Do superfused mast cells release histamine by endogenous cation exchange with potassium ions?

Isolated rat peritoneal mast cells released histamine on superfusion with isotonic salt solutions or isotonic deionized sucrose. The histamine release followed the kinetics of cation exchange characteristic of the release from similarly superfused isolated mast cell granules and histamine charged carboxylic resin IRC-50. The histamine release was accompanied by an efflux of potassium and ascribed to an endogenous cation exchange K+ in equilibrium with Hi+ occurring on the passage of outflowing potassium ions over histamine storing granules.