Effect of bupivacaine against acetylcholine and bradykinin induced tracheal tissue contraction of guinea pigs in vitro

Abstract

Background: Some inhaled local anaesthetics are effective in preventing airway constriction provoked by various stimuli. The objective of this study was to evaluate the protective effect of bupivacaine against acetylcholine (Ach) and bradykinin induced airway contraction of isolated tracheal tissue of guinea pig in vitro. Methods: It was a laboratory based randomized control trial, carried out in Pharmacology Department of Army Medical College Rawalpindi from January to December 2016. Effects of cumulative doses of acetylcholine (3–96 µg) and bradykinin (11–66 µg) in the presence of fixed dose of bupivacaine (2 mM) were observed on isolated tracheal smooth muscle of guinea pig by constructing cumulative dose response curves. Isometric Force Transducer DT-475 (USA) attached to PowerLab^® Data Acquisition Unit, was used to record the tracheal smooth muscle contractions. Results: Acetylcholine and bradykinin reversibly increased the tracheal muscle contractions of guinea pig. Maximum amplitude of contraction with acetylcholine and bradykinin alone and acetylcholine and bradykinin pretreated with lignocaine were 0.025±0.0009 mV, 0.013±0.0007 mV, 0.009±0.0005 mV, and 0.006±0.0006 mV respectively. Conclusion: Bupivacaine significantly inhibited the constrictor response of acetylcholine and bradykinin. The percent inhibition was more for acetylcholine than for bradykinin induced tracheal tissue contraction.

Pak J Physiol 2019;15(3):13?5