Biochemical evidence for two types of noradrenaline storage particles in rabbit iris

Centrifugation techniques were used to determine the subcellular distribution of noradrenaline (NA) and dopamine beta-hydroxylase (D beta H) in the rabbit iris. By application of isopycnic and differential gradient centrifugation methods 2 types of NA vesicles could be demonstrated. Of the total particle bound NA about 70% is associated with 'light' and about 30% with 'heavy' vesicles. For both types of vesicles the distribution of D beta H reflected that of NA.