Fast axoplasmic transport of noradrenaline and dopamine in mammalian peripheral nerve.

A fast transport of noradrenaline (NA) at a velocity of 392 mm/day was found in cat peroneal nerve using a double-ligation technique and a new sensitive radioenzymatic assay for catecholamines. The velocity of transport of NA is sufficiently close to that of 410 mm/day found for labelled proteins and polypeptides to be considered as moving down within the nerve fibres by the same transport mechanism. In addition, dopamine (DA) was also found to be moved down by anterograde transport at a fast, but not well defined, rate. Disulfiram, a dopamine-beta-hydroxylase inhibiting agent, reduced NA levels and increased DA both in control nerve segments and within the portion of the nerve isolated by ligations where NA-containing densecore vesicles are present. The results are considered to support a dynamic turnover of NA and DA in the dense-core vesicles as they are trasnported in the axons.