Postmortem changes of normetanephrine determined by a mass-fragmentographic technique in different rat brain areas

A specific and sensitive gas chromatographic-mass spectrometric assay for measurement of normetanephrine (NMN) in different rat brain regions is presented. The results show that hypothalamus contains the highest concentrations of the norepinephrine metabolite. An increase of NMN concentrations has been detected in animals killed by decapitation in comparison with microwave-irradiated rats. This finding has to be taken into consideration when NMN is measured in the brain in order to assess the functional activity of noradrenergic neurons.