Release and Uptake of Noradrenaline in Adrenergic Nerve Granules

A brief review is given of some recent findings concerning noradrenaline (NA)1release and uptake in isolated nerve granules and in connection with neurotransmissionin vivo.The main results are summarized in the following points. Rabbit heart granules have similar NA release rate and other properties as bovine nerve granules. Granules from the bovine vesicular gland show about 3 times lower NA release rate and differ in other respects from splenic nerve granules. Tyramine inhibits the uptake of NA in partially depleted isolated splenic nerve granules. Adrenergic a‐ and β‐blockers lower the NA release rate and inhibit NA uptake in splenic nerve granules, suggesting common features of the “receptor” mechanisms in granules and effector cells. Intermittent sympathetic nerve stimulation in decaborane depleted rabbits causes transmission failure which is partially overcome by “neuronal rest” and injection of NA or dopamine. Although homogenization experiments indicate that most of the NA in axones and nerve endings occur in granule bound form it is assumed that part of the NA is present as “transport NA” in loosely bound form available for immediate release.