Dimethyl sulfoxide decreases the fluorescence yield of the reaction between histamine and ortho-phthalaldehyde and may influence histamine release

Abstract

A sensitive method for quantifying histamine is the assay based on the fluorescence of the product obtained after reacting the amine with ortho-phthalaldehyde. The presence of dimethyl sulfoxide (DMSO) even in concentrations as low as 1% decreases the yield of fluorescence. Neglecting this quenching leads to the erroneous conclusion that DMSO in a concentration dependent manner inhibits the thapsigargin induced histamine release from peritoneal rat mast cells. Apart from the release induced by the selective calcium ion mobilizers thapsigargin and ionophore A23147, DMSO potently inhibits the response to other secretagogues.

Unusual effects of the ionophore A23187 at suboptimal concentrations in mast cell histamine release

“…The influence of solvents on cell responses is of great concern but we have not found effects of DMSO per se in the medium at concentrations below 1%, in agreement with others [5 -7]. Higher concentrations of DMSO inhibit histamine release [5][6][7] and it therefore seems unlikely that the increased potency of A23187 (Fig. 1) is due to interactions between the solvent and the mast cells.…”

In vitro inhibition of rat basophilic leukaemia mast cell (RBL-2H3) degranulation by novel indane compounds

“…2A and B). As previously reported [6], DMSO showed a quenching of the fl uorescence of the OPT adduct, but did not affect the degranulation. Moreover, PH2 and PH5 showed different profi les in the cytotoxicity assay; PH2 was found to be more cytotoxic than PH5 at higher concentrations, while the opposite trend was true at lower concentrations.…”

Analysis of Small Molecule Ligands Targeting the HIV-1 Matrix Protein-RNA Binding Site

“…As illustrated in Fig. 3A, in the absence of MA, increasing concentrations of DMSO or compounds in DMSO led to diminutions of FA signals, probably due to fluorescence quenching (75). However, in the presence of MA (Fig.…”