title: Presence and measurement of tele-methylhistamine in mast cells.
abstract: The histamine metabolite tele-methylhistamine (t-MH) was identified and measured in crude and purified peritoneal mast cells (MCs). Peritoneal dialysates, peritoneal cells, and purified MCs all contained t-MH in concentrations representing about 0.2% of the corresponding histamine (HA) levels. T-MH levels in crude cells represented about 70% of the total dialysate levels, indicating the presence of extracellular as well as intracellular t-MH. T-MH levels per MC in purified fractions were similar to those of crude fractions, indicating a MC origin for the intracellular t-MH. Histamine methyltransferase activity was not detected in crude or purified MC fractions, and incubations with the monoamine oxidase inhibitor pargyline failed to increase the content or release of t-MH in either fraction, suggesting a very slow or non-existent histamine methylation in MCs. Compound 48/80 produced a temperature-dependent release of HA and t-MH in crude and purified preparations, and Triton X-100 also released both amines. In all cases, the degree of release of both amines was correlated, consistent with a granular origin for t-MH in MCs. The low concentrations of t-MH in MCs do not necessarily indicate a role for MCs in HA metabolism, but suggest that t-MH may be a valuable marker for non-MC HA.
mesh_terms: D000818:Animals; D003902:Detergents / Q000494:pharmacology; D008401:Gas Chromatography-Mass Spectrometry; D006636:Histamine Release / Q000187:drug effects; D008297:Male; D008407:Mast Cells / Q000187:drug effects / Q000276:immunology*; D008761:Methylhistamines / Q000032:analysis* / Q000378:metabolism; D017830:Octoxynol; D010293:Pargyline / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013696:Temperature; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
chemical_list: D003902:Detergents; D008761:Methylhistamines; D011092:Polyethylene Glycols; D003189:p-Methoxy-N-methylphenethylamine; D017830:Octoxynol; D010293:Pargyline; C020404:tele-methylhistamine