Two pools of electron cytochemically demonstrable adenylate cyclase activity in cortical synaptosomes

Adenylate cyclase activity was demonstrated by means of electron microscopic cytochemistry in rat cortical synaptosomes incubated under various conditions. It was found that only the reaction at the postsynaptic density could be enhanced by noradrenaline and postmortem storage, while that on the presynaptic limiting membrane was insensitive to these effects but was affected selectively by vinblastine. On these grounds two different pools of cytochemically demonstrable adenylate cyclase activity were distinguished within the synaptic region.