Adler_1990_FEBS.Lett_267_107

The role of butyrylcholinesterase (BCHE) and acetylcholinesterase (AChE) in in regulating acetylcholine (ACh) lifetime was investigated by use of selective cholinesterase (ChE) inhibitors. Addition of 1 microM tetraisopropylpyrophosphoramide (iso-OMPA) led to a 98% inhibition of BCHE activity with little or no effect on AChE activity. This inhibition was accompanied by a 26% increase in the amplitude and a 43% prolongation in the half-relaxation time of contractions elicited by electric field stimulation (EFS). Coapplication of BW 284C51 (a selective AChE inhibitor) and 1 microM iso-OMPA resulted in increases of 2-fold in the amplitude and 10-fold in the half-relaxation time of EFS-induced contractions. These alterations were accompanied by small but sustained baseline contractures that were antagonized completely by incubation with exogenous BCHE (2.5 U/ml). The results suggest that BCHE serves to coregulate the lifetime of ACh in canine tracheal smooth muscle.