| Abstract: | The effect of corticosterone on effector cell response to noradrenaline in vivo and on extraneuronal amine uptake in vitro has been investigated in rat submaxillary glands. When tissue slices were incubated with [3H]noradrenaline the level of extraneuronally retained radioactive material was found to be markedly reduced at a concentration of 10 μg ml?1 of corticosterone after inhibition of neuronal uptake by protriptyline. Corticosterone in a dose of 10 mg kg?1 was found to markedly potentiate the secretory response to noradrenaline in vivo, when the neuronal uptake of noradrenaline was blocked by protriptyline (10 mg kg?1, i.p.). Inhibition of neuronal uptake alone by protriptyline or of the extraneuronal uptake alone by corticosterone in the doses used here did not affect the dose-response curve for noradrenaline, at least not in its lower part. The data thus clearly show that the extraneuronal amine uptake of rat salivary glands is blocked by corticosterone and that this extraneuronal uptake might be regarded as a mechanism of importance for the inactivation of the adrenergic transmitter. |
