Changes in Membrane Potential on Histamine Release from Mast Cells: Measurement with a Fluorescent Dye

Abstract

Changes in fluorescence intensity of a thiocarbocyanine dye (diS-C₃-(5)) were monitored in rat peritoneal mast cells in the presence of histamine releasers. Compound 48/80, a specific histamine releaser, increased fluorescence intensity which reached a maximum in 3-4 min ; thereafter it gradually returned to a steady state. These changes in the fluorescence intensity were dependent upon the ionic environment and the energy state of the mast cells. By contrast, histamine release from mast cells induced by comp. 48/80 was completed within 10 sec. These data indicate that the comp. 48/80-induced histamine release is not directly associated with the change in membrane potential except at the onset.