Serotonin uptake and release by biochemically characterized nerve endings isolated from rat brain by concomitant...

Crude synaptosomal preparations of rat brain were separated by concomitant flotation and sedimentation in a sucrose gradient into fractions containing myelin, nerve endings, and mitochondria, respectively. Two myelin-free nerve ending fractions were obtained which differ in the serotonin content and the activities of the enzymes 5-hydroxytryptophan decarboxylase, monoamine oxidase, choline acetylase, and acetylcholin-esterase. In glucose medium sodium ions stimulate serotonin uptake into the nerve endings while potassium ions in sucrose solution induce the release of this amine.