The metabolic pattern of spontaneously released [3H]norepinephrine in the presence of uptake inhibitors.

The effect of uptake inhibitors on the spontaneous release of [3H]norepinephrine was studied using rat isolated vas deferens. Cocaine, desmethylimipramine, phenoxybenzamine, and guanethidine caused an increase in the spontaneous outflow of tritium, but did not alter the metabolic pattern of released [3H]norepinephrine. Bretylium caused an increase of both total tritium outflow and norepinephrine content. It is suggested that these drugs caused release of norepinephrine from storage sites and that norepinephrine was metabolized within the nerve terminals before reaching the biophase.