Airway smooth muscles (ASMs) play an essential role during breathing by contracting and relaxing as needed. Its dysfunction is related to some diseases such as asthma. The contractile mechanism of ASMs is complex. Therefore, research is necessary for this domain to identify issues and chemicals that can affect their contractions and impose health threats. This study aimed to investigate the effects of fluoxetine on the smooth muscles of the ASM using an isolated organ bath system. Fifteen male Sprague Dawley rats were divided into three groups: acetylcholine (ACh) group, fluoxetine group, and ACh + fluoxetine group. Following decapitation, 1-cm-long smooth muscle strips were prepared and placed in the isolated organ bath system Krebs' solution at 37 °C (pH = 7.4), constantly bubbled with oxygen/carbon dioxide mixture (95%:5%), and isometric contractions were recorded. Contraction of the smooth muscle was achieved by 10-µM Ach, and contractile/relaxation effects of cumulative concentrations of fluoxetine (10-9-10-1 M) were investigated. There was a numerical decrease in the contraction compared to ACh with no statistical significance in the ACh-fluoxetine group. There was a significant difference between the fluoxetine and the ACh groups (p < 0.05). In conclusion, fluoxetine had no contractile effect on ASM in isolated organ bath systems. Future studies are needed to evaluate the effects of oral usage of fluoxetine on the bronchial muscle in different experimental models to explain the adverse/beneficial effects of fluoxetine in the subjects, especially with respiratory conditions.
Keywords: Acetylcholine; Airway smooth muscles; Fluoxetine; Organ bath system; Respiratory system.
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