Pre- and postsynaptic localization of central muscarinic receptors.

3H-Quinuclidinyl benzylate and dimethyl 14C-d-tubocurarine were used to localize muscarinic and nicotinic receptors in synaptosomal membranes of the rat cerebral cortex. The results obtained, after the action of different concentrations of Triton X-100, suggest that, while nicotinic receptors are postsynaptic, the muscarinic ones are both pre- and postsynaptic.