Regulatory role of extracellular Na+ and Ca2+ ions in nerve growth factor induced histamine secretion from rat mast cells.
OBJECTIVE
This study was aimed to investigate effects of extracellular Na+ and Ca2+ ions on nerve growth factor (NGF) induced histamine release from mast cells.


METHODS
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.
Stempelj
M
M
Institute of Pharmacology and Experimental Toxicology, Faculty of Medicine, University of Ljubljana, Korytkova 2, SI-1000 Ljubljana, Slovenia. mateja.stempelj@mf.uni-lj.si
Carman-Krzan
M
M
Ferjan
I
I
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism*; D006636:Histamine Release / Q000187:drug effects; D008297:Male; D008407:Mast Cells / Q000187:drug effects / Q000378:metabolism*; D020932:Nerve Growth Factor / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism*; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors
D019831:Sodium-Calcium Exchanger; D000584:Amiloride; D020932:Nerve Growth Factor; D012964:Sodium; D002118:Calcium