Distribution of acceptors for beta-bungarotoxin in the central nervous system of the rat.

High-affinity acceptors for 125I-beta-bungarotoxin have been identified on rat brain cryostat sections and mapped quantitatively using 3H-sensitive sheet film autoradiography. A unique distribution of acceptors has thus been observed; the toxin sites are particularly enriched in grey matter areas and synaptic regions, consistent with the pharmacological action of beta-bungarotoxin. As the binding was abolished by dendrotoxin, a related polypeptide known to inhibit fast-activating K+ conductances, the occurrence of beta-bungarotoxin acceptors may indicate the location of certain voltage-sensitive K+ channels. The overall distribution is, however, distinct from that of any other ion channel described.