Phospholipase A (EC 3.1.1.4) and phospholipase C (EC 3.1.4.3) were used for studying the role of phospholipid of synaptosomal membrane on norepinephrine uptake activity. Synaptosomes were isolated from cerebral cortex of guinea pigs and treated with phospholipase A or phospholipase C before the uptake experiments. Treatment of synaptosomes with phospholipase A has resulted in severe inhibition of norepinephrine-uptake. Under similar conditions, the activity of synaptosomal (Na + K)-