Autoradiography of dendritic acetylcholine receptors: a method for study of isolated neurons of the adult central nervous system in the turtle.

Adult neurons were isolated from turtle retina in order to study the subcellular distribution of muscarinic acetylcholine receptors. Retinas were perfused in vitro with [3H]quinuclidinylbenzilate [3H]QNB) to label muscarinic receptors, and individual neurons with extensive dendritic arborization were obtained for autoradiography by use of papain and trituration. Papain caused no change in the number of muscarinic receptor sites nor in their affinity for [3H]QNB. Receptors, indicated by the positions of silver grains, were localized to dendritic processes.