Biomedical subjects

A L Rönnberg

Publications and source records attributed to A L Rönnberg.

15 recordsLinked to original sources

PubMed1984

A simplified procedure for the fluorometric determination of histamine in rat stomach.

Histamine can be determined fluorometrically by the use of o-phthaldialdehyde. Over the years, the fluorometric procedure has been made more sensitive and more specific through modifications of the reaction conditions. As a consequence the method now allows the direct measurement of histamine in crude trichloroacetic acid extracts of rat gastric mucosa and peritoneal mast cells. This conclusion is corroborated by the results of high performance liquid chromatography of the o-phthaldialdehyde-induced fluorophores in the extracts.

Animals↗

PubMed1984

Reaction of histamine with o-phthalaldehyde: isolation and analysis of the fluorophore.

Histamine reacts with o-phthalaldehyde (OPT) to form colored as well as highly fluorescent derivatives. After large-scale synthesis, the chromophores were eliminated and the pale yellowish fluorophore was isolated by a series of chromatographic steps, followed by semipreparative high-performance liquid chromatography. Structural analysis of the fluorophore was performed using NMR and mass spectrometry. The isolated fluorophore was found to be a condensation product of 2 molecules of OPT and 1 molecule of histamine, arranged to form a complex dihydrophenantroline derivative with a quaternary amine group. The molecular weight of its chloride salt was 379.5. It was shown that the fluorophore exists in aqueous milieu as an equilibrium between three isomers.

Aldehydes↗

PubMed1984

High-performance liquid chromatographic determination of histamine in biological samples after derivation with o-phthalaldehyde.

A high-performance liquid chromatographic (HPLC) method for the determination of histamine in tissues, based on precolumn derivation with o-phthalaldehyde, is described. Trichloroacetic acid extracts of rat brain, but not of rat stomach or of rat peritoneal mast cells, had to be cleaned-up by a chromatographic step before HPLC. The extracts were allowed to react with o-phthalaldehyde at pH 12.5 and -20 degrees C for 12 h, followed by acidification to pH 2.0. HPLC was performed on a reverse-phase column with isocratic elution using sulfuric acid in methanol as solvent system. A fluorescence detection system was used; excitation was set at 353 nm and emission was read at 451 nm. One chromatographic run was completed in 20 min. The detection limit with the conventional procedure was 1.5 ng histamine per sample, with a scaled-down procedure it was 250 pg per sample. With extracts of rat gastric mucosa the within-run variation was 2.7% and the day-to-day variation 4.5%.

Aldehydes↗

PubMed1977

Regional distribution of mast cells containing histamine, dopamine, or 5-hydroxytryptamine in the mammalian brain.

Brain mast cells were studied in mice, rats, rabbits, hamsters, guinea pigs, cats, cows, monkeys, and humans with use of a variety of techniques. They were localized by staining with Astrablau or by toluidine blue-induced metachromasia and characterized by their ultrastructural appearance and by the presence of histochemically demonstrable histamine (o-phthaldiadehyde fluorescence method). The identity of the fluorophore was secured by microspectrofluorometry. Mast cells in brain usually had a perivascular localization but were also found scattered in the parenchyma. The regional variations in the number of mast cells agreed with the histamine concentration as measured fluorometrically. The variation was in the order leptomeninges greater than hypothalamus greater than cerebral cortex = mesencephalon greater than cerebellum = brain stem. In addition to histamine, murine mast cells stored serotonin, whereas bovine mast cells contained dopamine, visualized histochemically by the formaldehyde technique.

Animals↗

PubMed1974