Receptor protection experiments confirm the identity of presynaptic alpha sub(2)-autoreceptors

Receptor protection experiments were carried out in cerebrocortical slices from rabbits in order to study the sites at which drugs with alpha -adrenoceptor affinity modulate the release of noradrenaline. The slices were preincubated with super(3)H-noradrenaline. Phenoxybenzamine was added from 85 to 95 min of superfusion. Potential protecting drugs were present for 5 min before and during the exposure to phenoxybenzamine and then washed out together with the latter. It is concluded that drugs with affinity for alpha sub(2)-adrenoceptors protect the noradrenergic axons of rabbit brain cortex against the long-lasting release-enhancing effect of phenoxybenzamine.