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Updated: Oct 18, 2026
Analyzing the Functions of Mast Cells In Vivo Using 'Mast Cell Knock-in' Mice
Published on: May 27, 2015
Differential quantal release of histamine and 5-hydroxytryptamine from mast cells of vesicular monoamine transporter
E R Travis1, Y M Wang, D J Michael
1Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599, USA.
Abstract:
The recent availability of mice lacking the neuronal form of the vesicular monoamine transporter 2 (VMAT2) affords the opportunity to study its roles in storage and release. Carbon fiber microelectrodes were used to measure individual secretory events of histamine and 5-hydroxytryptamine (5-HT) from VMAT2-expressing mast cells as a model system for quantal release. VMAT2 is indispensable for monoamine storage because mast cells from homozygous (VMAT2(-/-)) mice, while undergoing granule-cell fusion, do not release monoamines. Cells from heterozygous animals (VMAT2(+/-)) secrete lower amounts of monoamine per granule than cells from wild-type controls. Investigation of corelease of histamine and 5-HT from granules in VMAT2(+/-) cells revealed 5-HT quantal size was reduced more than that of histamine. Thus, although vesicular transport is the limiting factor determining quantal size of 5-HT and histamine release, intragranular association with the heparin matrix also plays a significant role.
