Objective: Paracetamol is a pharmacologic agent widely used as analgesic and antipyretic. Like many pharmacologic agents, it has been thought that it may have activity on different systems. In this context, it has been shown to cause inhibition on the contractile activity of uterine and bladder smooth muscle. It is not known whether paracetamol has an effect on another smooth muscle, the bronchus. This study aimed to investigate the possible effect of paracetamol on the contractile activity of bronchial smooth muscle of female rats.

Materials and Methods: 3mm ring-shaped strips were obtained from the removed bronchi of adult female Sprague-Dawley rats in diestrus. Under 1.5 g tension, they were suspended in isolated organ baths containing Krebs solution (n=8). After the regulation period, 0.1 M paracetamol was first applied. The tissues were then washed and 0.1 M paracetamol was applied upon induction with 10 μM acetylcholine(Ach). Maximal contraction values(Emax) before and after the application were normalized as % change. Paired t test and Student’s t test were used to evaluate the data statistically.

Results: Paracetamol caused a statistically significant decrease in both non-Ach-induced (p<0.05) and induced (p<0.001) bronchial smooth muscle contractile activity. It caused stronger inhibition of Ach-induced bronchial smooth muscle contractile activity (p<0.05).

Conclusion: Paracetamol was shown to cause an inhibitory effect on both basal and Ach-induced bronchial contraction.