AbstractThe noradrenaline content was determined in intact and atrophied rat salivary glands at different time intervals after reserpine treatment, both with and without previous monoamine oxidase inhibition. After reserpine administration there was no significant difference between the two glands in the rate of noradrenaline disappearance. The loss of noradrenaline was somewhat accelerated in rats given dry wheat starch (a procedure which has been shown to increase the impulse flow of the adrenergic nerves to the salivary glands), showing that the impulse flow in the adrenergic nerves influences the noradrenaline reduction. After monoamine oxidase inhibition reserpine produced a much slower noradrenaline reduction rate. After this treatment a slower decrease was observed in the atrophied glands than in the intact ones. The data in this study indicate that most of the noradrenaline after reserpine treatment is metabolized by means of intraneuronally localized monoamine oxidase.