Degradation of acetylcholine in human airways: role of butyrylcholinesterase

Abstract

1 Neostigmine and BW284C51 induced concentration-dependent contractions in human isolated bronchial preparations whereas tetraisopropylpyrophosphoramide (iso-OMPA) was inactive on airway resting tone. 2 Neostigmine (0.1 pM) or iso-OMPA (100 pM) increased acetylcholine sensitivity in human isolated bronchial preparations but did not alter methacholine or carbachol concentration-effect curves. 3 In the presence of iso-OMPA (10 pM) the bronchial rings were more sensitive to neostigmine. The pD2 values were, control: 6.05 ± 0.15 and treated: 6.91 ± 0.14.4 Neostigmine or iso-OMPA retarded the degradation of acetylcholine when this substrate was exogenously added to human isolated airways. A marked reduction of acetylcholine degradation was observed in the presence of both inhibitors. Exogenous butyrylcholine degradation was prevented by iso-OMPA (1O pM) but not by neostigmine (O.1 pM). 5These results suggest the presence of butyrylcholinesterase activity in human bronchial muscle and this enzyme may co-regulate the degradation of acetylcholine in this tissue.

Aclidinium inhibits cholinergic and tobacco smoke-induced MUC5AC in human airways

“…Carbachol was selected as a cholinergic agonist as it is widely used in the literature and is resistant to degradation by cholinesterases present in human bronchial epithelium [13]. In this study we used carbachol at 100 mM concentration, since we observed that it was near maximal responses, which is in keeping with other studies of goblet cell secretion and cell culture models using cholinomimetics [14].…”

Liver function tests in patients with bacteremia

“…However, the half-life of cholinesterase in plasma is about 10 days, and increases in its consumption rate are more important to consider than poor synthesis in acute inflammation of bacteremia. Some reports have suggested a role for serum cholinesterase in lipid metabolism (15), a controlling role in the permeability of membranes (16), and a role in the coregulation of the degradation of acetylcholine (17). It has not been clear whether the serum cholinesterase level decreases rapidly in patients with sepsis.…”

Cholinesterase Its significance in anaesthetic practice

“…From the results of their experiments on isolated human lung preparations, Norel et al [12] suggest a rôle for plasma cholinesterase in the co-regulation of the degradation of acetylcholine. They claim that neurotransmitter hydrolysis may be controlled via two enzymatic pathways: the primary system is acetylcholinesterase for the acetylcholine, which is held in the synaptic cleft and the secondary system, using plasma cholinesterase, for the extraneuronal acetylcholine which has diffused into the smooth muscle regions.…”