A thin‐layer chromatographic procedure for the assay of labelled noradrenaline and its metabolites in tissues and in incubation medium

A method for the extraction, separation and quantitative determination of [³H]noradrenaline [³H‐NA] and its five major metabolites has been devised using thin layer chromatography. This procedure was used to study the pattern of ³H‐NA and its metabolites in the total radioactivity of the tissues and that released spontaneously from the rat isolated vas deferens. Whereas in tissues ³H‐NA represented almost all of the total radioactivity (94·8 ± 0·47%), in the samples of spontaneous outflow it represented only 16·8 ± 2·1%. The rest was mostly accounted for by the five metabolites, primarily ³H‐DOPEG and ³H‐MOPEG. These findings show that in the rat vas deferens ³H‐NA is preferentially metabolized via the two glycol derivatives, i.e. ³H‐DOPEG and ³H‐MOPEG.