Inhibitory Action of Adrenergic Blocking Agents on Reuptake and Net Uptake of Noradrenaline in Nerve Granules

The effect of various adrenergic blocking agents on the reuptake and net uptake of noradrenaline (NA) in isolated adrenergic nerve granules has been studied. All of the α‐ and β‐blockers tested exerted an inhibitory action on the spontaneous release rate of NA from granules and also on the reuptake of 3 H‐labelled NA from a medium containing 1–3×10 ‐6 M NA. The highest activity was shown by the α‐blockers dihydroergotamine and Plegicil, but some β‐blockers were almost as active. No significant difference in inhibitory action was observed between the l‐ and d‐isomers of propranolol and Aptin. In the presence of ATP and NA 5 × 10 ‐6 M‐10 ‐4 M, the net uptake of NA in partially depleted granules was strongly inhibited by the same blocking agents as were most active on the reuptake. The present results confirm the previous finding that adrenergic blocking agents, both of the α and β‐type, inhibit NA uptake in nerve granules. The possible mediation of transmitter release and uptake by granule receptors is discussed.