The investigation of fluoxetine effects on the bronchial smooth muscles by the isolated organ bath system

Airway smooth muscles (ASMs) are present in the respiratory system at the trachea and play a major role into protecting mechanical stability during breathing by contracting and relaxing as needed. Dysfunctionality in ASMs is directly related to respiratory system diseases, such as asthma and Chronic Obstructive Pulmonary Disease. The contractile mechanism of ASMs is complex. Therefore, research is necessary in this domain to identify issues and chemicals that can affect their contractions and impose health threats. This study investigated the effects of fluoxetine on the smooth muscles of the ASM using an isolated organ bath system. Sprague Dawley rats used for the study were divided into 3 different groups following; spontaneous contractions with fluoxetine-added group from 10-9 to 10-1 concentrations (Fluoxetine; n = 6), the group induced by acetylcholine (Ach; n = 6) and acetylcholine induced fluoxetine group which fluoxetine concentrations are from 10-9 to 10-1 (Ach + Fluoxetine, n = 6). Sprague Dawley rats were sacrificed, and primary bronchial tissues were dissected and taken into Krebs solution. Primary bronchial tissues were suspended in the organ bath. After basal recordings, the strain was increased to 1.5 grams and the pharmacological agents were applied to respective groups. As a result of the experiment, in the acetylcholine-fluoxetine group has numerical decrease in comparison with acetylcholine with no statistical significance. On the other hand, there was a significant difference between the fluoxetine-only group and the acetylcholine-only group (*p <0.05). In contrast to acetylcholine, which provides a strong contraction, fluoxetine has no such constrictive effect. The present study may contribute to the literature in this sense; therefore, future studies can be developed to evaluate the effects of oral usage of fluoxetine on the bronchial muscle in different experimental models. Keywords: airway smooth muscles, fluoxetine, SSRI, organ bath system