The recovery of the capacity for uptake-retention of ( 3 H)noradrenaline in rat adrenergic nerves after reserpine

The uptake retention of [³H]noradrenaline (2.5 μg/kg, i.v., 30 min before death) in rat salivary glands was studied at different times after reserpine treatment (10 mg/kg, i.p.). The effect of removing the cervical superior ganglion 12 h before death on the recovery of the [³H]noradrenaline uptake-retention capacity after reserpine was also investigated. The ganglionectomy was unilateral, and the contralateral side was always preganglionically denervated. In glands with uninterrupted postganglionic adrenergic nerves the onset of recovery of the [³H]noradrenaline retention capacity occurred 24–36 h after reserpine. Normal contents were found on the second to third days. Between day 3 and 6 a possible overshoot of [³H]nor- adrenaline content, followed by normal and subnormal contents (7–21 days) were recorded. Ganglionectomy, 12 h before death, markedly delayed the recovery of [³H]noradrenaline retention capacity. Both the recovery curve for [³H]noradrenaline retention in glands with intact postganglionic nerves, and the effect of ganglionectomy on the [³H]noradrenaline retention capacity, were clearly related to the relative number of new functioning amine granules that are transported via the axons to the nerve terminals at different times after the reserpine-pretreatment. The results indicate that young amine granules, recently transported to the nerve terminals via the axons, have the greatest capacity to take up and retain [³H]noradrenaline. The half-life of this capacity in the young granules appears to be about 12 h. Since published results indicate that [³H]noradrenaline is initially taken up in the “small easily releasable pool” of transmitter, we suggest that young amine granules are of the greatest importance for adrenergic function, i.e. that they are particularly active in taking up recaptured noradrenaline, in the synthesis, and in the release of this transmitter.