Inhibition of nicotinic responses at neuromuscular junctions by 3,3-dimethyl-1-butanol carbamate (DBC)

Abstract

The action of 3,3-dimethyl-1-butanol carbamate (DBC), a synthetic carbachol analogue in which the quaternary nitrogen atom has been replaced by a carbon atom, has been studied in relation to its effects on nicotinic responses. In the thick biventer cervicis nerve-muscle preparation and frog rectus abdominis muscle preparation, DBC inhibited the responses elicited by nicotine and dimethylphenylpiperazinium at concentrations that did not affect responses induced by acetylcholine. DBC ( −4–10 −3M) depressed markedly the uptake of 3H-nicotine (2 × 10 −3M) into the frog rectus abdominis muscle preparation. In the innervated chick biventer cervicis nerve-muscle preparation, DBC (10 −3M) also decreased the uptake of 3H-nicotine (2 × 10 −3M), but in denervated preparations, DBC had no effect. It is concluded that the peripheral antinicotinic actions of DBC require an intact nerve-muscle junction and are due to a blockade in the uptake of nicotine into nerve fibers.