Storage and release of noradrenaline in hypothalamic synaptosomes

The noradrenaline storage capacity of vesicles in hypothalamic synaptosomes was measured by incubating them with [3H]noradrenaline under saturating conditions. The normal noradrenaline content is 52% of storage capacity. Incubation or superfusion with 50 mM-potassium causes calsium-dependent release from the vesicles. Such release reduces not only the vesicular content, but also the noradrenaline storage capacity. This suggests that after exocytosis vesicles cannot refill with noradrenaline.