pros-Methylimidazoleacetic Acid in Rat Brain: Its Regional Distribution and Relationship to Metabolic Pathways of Histamine

pros-Methylimidazoleacetic acid (p-MIAA; 1-methylimidazole-5-acetic acid), an isomer of the histamine metabolite, tele-methylimidazoleacetic acid (t-MIAA), is present in brain and CSF. Its relationship to histamine synthesis and catabolism was assessed in brains of rats. p-MIAA distribution in brain regions was heterogeneous although the concentrations in regions with the highest (hypothalamus) and the lowest (medulla-pons) levels differed less than four-fold. There was no significant correlation between the regional distributions of p-MIAA with those of histamine or its metabolites. pros-Methylhistidine (1 g/kg, i.p.) produced a 20-fold increase in mean levels of p-MIAA and up to a 50-fold increase in levels of pros-methylhistamine (p-MH), a putative intermediate; levels of histamine and its metabolites were unaltered. L-Histidine (1 g/kg, i.p.) or alpha-fluoromethylhistidine (100 mg/kg, i.p.), the irreversible inhibitor of histamine synthesis, did not alter the levels of p-MIAA in brain. Like the levels of t-MIAA, the levels of p-MIAA were unaltered after probenecid administration. Contrary to its effects in lowering t-MIAA levels, pargyline (75 mg/kg, i.p.) produced a slight rise in levels of p-MIAA in all regions. These findings suggest that, in brain, the metabolic pathways of histamine are independent of pathways that generate p-MIAA. Further, since brain is capable of p-MH formation, its use as an internal standard in analytical methods merits caution.     

Inaktivierung des Salmonella-Bakteriophagen P22 durch Chloroform

Ohne ZusammenfassungTeil einer Habilitationsschrift an der Naturwissenschaftlichen Fakultät der Johann Wolfgang Goethe-Universität Frankfurt a.M.     

Die Grenzen der Mendelschen Vererbung

Ohne Zusammenfassung     

Reine Kette, Genospezies und Stirps

Ohne Zusammenfassung     

Die Uniformität der Bastarde

Ohne Zusammenfassung     

Zur Begriffsbildung in der Phänogenetik (II)

Ohne Zusammenfassung     

Messung nichtosmotoscher Wasseraufnahme an plasmolysierten Protoplasten

Ohne ZusammenfassungMit 3 Textabbildungen.