Dexamethasone reduces the high-affinity binding of hemicholinium-3 to rat phrenic nerve endings in vitro: an autoradiographic study.

Receptor autoradiography has revealed high-affinity binding sites for hemicholinium-3 (HC-3) in the phrenic nerve endings of rat diaphragm. It has been demonstrated that 200 nM dexamethasone (Dex) in vitro reduces the binding of HC-3 to these high-affinity sites. It seems likely that the decrease in inhibitory effects of HC-3 on choline uptake and acetylcholine synthesis in rat diaphragm caused by Dex, should be the result of an interference of Dex with the binding of HC-3 to its high affinity sites.