DETERMINATION OF RELAXANT EFFECT OF ROPIVACAINE AGAINST ACETYLCHOLINE AND BRADYKININ INDUCED AIRWAY CONTRACTION OF GUINEA PIGS

Abstract

Objective: To study the relaxant effect of ropivacaine against acetylcholine and bradykinin induced airway contraction of isolated tracheal tissue of guinea pig in vitro.

Study Design: Laboratory based experimental study.

Place and Duration of Study: Pharmacology department at Army Medical College, Rawalpindi, from Feb 2016 to Dec 2016.

Methodology: Response of variable doses of acetylcholine (10-6-10-3 M) and bradykinin (11μg-66 μg) in the presence of fixed dose of ropivacaine (1mm) were observed on isolated tracheal smooth muscle of guinea pig by constructing cumulative dose response curves. Isometric Force Transducer DT-475 (USA) attached to Power Lab Data Acquisition Unit, was used to record the tracheal smooth muscle contractions. For data analysis labchart software was used.

Results: Acetylcholine and bradykinin enhanced the tracheal muscle contractions of guinea pig. Amplitude of contraction with acetylcholine and bradykinin alone & acetylcholine and bradykinin pretreated with ropivacaine were 0.025 ± 0.0009 mV, 0.013 ± 0.0007 mV, 0.010 ± 0.0008 mV and 0.006 ± 0.0002 mV respectively. So ropivacaine significantly reversed acetylcholine and bradykinin induced contraction.

Conclusion: Ropivacaine significantly ameliorated the constrictor response of acetylcholine and bradykinin. The percent inhibition was more for acetylcholine than for bradykinin induced tracheal tissue contraction. Ropivacaine may be used as spinal anesthesia in asthmatic patients prior to surgeries as a bronchodilator.