The acetylcholinesterase inhibitor BW284c51 is a potent blocker of Torpedo nicotinic AchRs incorporated into the Xenopus oocyte membrane

Abstract

1 This work was aimed to determine if 1,5-bis(4-allyldimethylammoniumphenyl)pentan-3-one dibromide (BW284c51), the most selective acetylcholinesterase inhibitor (AchEI), affects the nicotinic acetylcholine (Ach) receptor (AchR) function. 2 Purified Torpedo nicotinic AchRs were injected into Xenopus laevis oocytes and BW284c51 effects on Ach-and carbamylcholine (Cch)-elicited currents were assessed using the voltage-clamp technique. 3 BW284c51 (up to 1 mM) did not evoke any change in the oocyte membrane conductance. When BW284c51 (10 pM-100 mM) and Ach were coapplied, Ach-evoked currents (I Ach ) were reversibly inhibited in a concentration-dependent manner (Hill coefficient, 1; IC 50 , 0.2-0.5 mM for 0.1-1000 mM Ach). Cch-elicited currents showed a similar inhibition by BW284c51. 4 I Ach blockade by BW284c51 showed a strong voltage dependence, being only apparent at hyperpolarising potentials. BW284c51 also enhanced I Ach desensitisation. 5 BW284c51 changed the Ach concentration-dependence curve of Torpedo AchR response from two-site to single-site kinetics, without noticeably affecting the EC 50 value. 6 The BW284c51 blocking effect was highly selective for nicotinic over muscarinic receptors. BW284c51 inhibition potency was stronger than that of tacrine, and similar to that of d-tubocurarine (d-TC). Coapplication of BW284c51 with either tacrine or d-TC revealed synergistic inhibitory effects. 7 Our results indicate that BW284c51 antagonises nicotinic AchRs in a noncompetitive way by blocking the receptor channel, and possibly by other, yet unknown, mechanisms. 8 Therefore, besides acting as a selective AchEI, BW284c51 constitutes a powerful and reversible blocker of nicotinic AchRs that might be used as a valuable tool for understanding their function.

Muscle-Type Nicotinic Receptor Modulation by 2,6-Dimethylaniline, a Molecule Resembling the Hydrophobic Moiety of Lidocaine

“…Furthermore, the dose-response curve shifted to the right ( Figure 7B ), increasing significantly the EC 50 up to 63 μM (confidence interval, 50–96 μM) and decreasing the slope to 1.3 ± 0.1. A similar reduction in the slope of the ACh concentration- I ACh amplitude relationship was found when co-applying ACh with the quaternary-ammonium BW284c51 (Olivera-Bravo et al, 2005) or lidocaine (Alberola-Die et al, 2011), though the mechanisms underlying this effect remains unclear, since it is only partially dependent on the increase of nAChR desensitization caused by these drugs (Alberola-Die et al, 2011). Nonetheless, given that the percentage of I ACh inhibition was also dependent on ACh concentration, nAChR blockade by DMA was not exclusively a non-competitive antagonism.…”

Recombinant expression and biochemical characterization of the catalytic domain of acetylcholinesterase-1 from the African malaria mosquito, Anopheles gambiae

“…acetylthiocholine iodide (ATC), acetyl-(β-methyl)thiocholine iodide (AβMTC), 1,5-bis(4-allyldimethylammoniumphenyl)-pentan-3-one dibromide (BW284C51) (Olivera-Bravo et al, 2005), propionylthiocholine iodide (PTC), S -butyrylthiocholine iodide (BTC), 5,5-dithio-bis(2-nitrobenzoic acid) (DTNB), choline chloride, eserine hemisulfate, ethopropazine hydrochloride, and carbaryl were purchased from Sigma-Aldrich (St. Louis, MO). Paraoxon (O,O'-diethyl p -nitrophenyl phosphate, >99%, the active metabolite of parathion) and malaoxon (O,O'-dimethyl S-(1,2-dicarbethoxy)ethyl phosphorothioate, >99%) were both purchased from Chem Service (West Chester, PA).…”

Lidocaine effects on acetylcholine-elicited currents from mouse superior cervical ganglion neurons

“…This being of particular interest because many molecules acting on nAChRs have marked specificity on particular subtypes. So, for instance, whereas BW284c51, a quaternaryammonium cholinesterase inhibitor, is a powerful inhibitor of muscle-type nAChRs (Olivera-Bravo et al, 2005 it barely blocks either heteromeric α4β2 or homomeric α7 nAChRs (Fayuk and Yakel, 2004). Similarly, niflumic and flufenamic acids inhibit α3β2 but potentiate α3β4 nAChRs (Zwart et al, 1995).…”