Regulatory role of extracellular Na+ and Ca2+ ions in nerve growth factor induced histamine secretion from rat mast cells.

Objective And Design: This study was aimed to investigate effects of extracellular Na+ and Ca2+ ions on nerve growth factor (NGF) induced histamine release from mast cells.

Material: Isolated peritoneal mast cells were obtained from male Wistar rats.

Methods: Cells were suspended in solution with different concentration of Na+ and Ca2+ ions and stimulated with NGF. Histamine release was assayed spectrofluorometrically.

Results: NGF (0.001-1 microg/ml) dose-dependently releases histamine from mast cell at physiological extracellular Na+ (134 mM) and Ca2+ (1 mM) conditions. Lowering extracellular Ca2+ ions to 0.1 mM reduced histamine response to nearly basal level. However, the removal of extracellular Na+ ions significantly enhanced the secretion provoked by NGF (0.6 microg/ml) in low Ca2+ medium. Amiloride, an inhibitor of Na+/Ca2+ and Na/H+ exchangers inhibited the potentiating effect of sodium free conditions.

Conclusions: Our results suggest that the activity of Na+/Ca2+ and/or Na+/H+ exchange mechanisms could be of particular importance in the secretory process of mast cells induced by NGF.