Axonal Transport of Adrenaline, Noradrenaline and Phenylethanolamine-N-methyl Transferase (PNMT) in Sympathetic Neurons of the Cod, Gadus Morhua

The axonal transport of adrenaline, noradrenaline and phenylethanolamine-N-methyl transferase (PNMT) has been studied in vivo in sympathetic neurons of the splanchnic nerve in the cod, Gadus morhua. Adrenaline and noradrenaline are transported at a mean axonal transport rate of 16 mm/day. After correction for a non-mobile fraction of adrenaline and noradrenaline, which does not contribute to the amine accumulation proximal to a ligature, a maximal rate of transport was calculated to about 45 mm/day for both amines. The increased level of catecholamines in front of a ligature could be depleted by reserpine treatment, which strongly suggests that both amines are stored in granules. PNMT is transported at a slow rate of 2 mm/day. The subcellular distribution of the cod PNMT was exclusively non-particular. The cod PNMT was further characterized by studying substrate specificity, temperature and pH optima. It is concluded that adrenaline and noradrenaline, stored in granules, are transported in a proximo-distal direction at a high rate compared to PNMT.