The pharmacological effects of ozone on isolated guinea pig tracheal preparations

Ozone is a potent oxidizing agent with a variety of potential uses, including its antimicrobial and deodorising properties. The recent increased use of ozone led to questions regarding its safety in humans. This study specifically focussed on the in vitro effect of ozone on isolated guinea pig tracheal tissue as well as its effect on the isolated trachea in the presence of various drugs with well-known effects, including methacholine and isoproterenol. The results found in this study identified two direct effects on the isolated trachea due to ozone exposure: (1) a definite contraction of the isolated trachea immediately after exposure to ozone, and (2) a clearly visible and significant hyper responsiveness of the isolated trachea to irritants, e.g. methacholine. Although ozone has a negative effect on the trachea, it was concluded that ozone has no adverse effect on muscarinic receptors. We found that ozone has a significant desensitizing effect on the pharmacological response of β sympathomimetics (isoproterenol), while isoproterenol itself has a relaxing effect on the ozone-induced contraction of the isolated trachea. Observations in this in vitro study further emphasised that ozone does have a negative effect on respiratory health. It is underlined that the inhalation of ozone should be avoided by workers who are often in contact with the gas, and especially by those with existing airway diseases. An apparent EC₅₀ value of ozone on the trachea was established by two different methods as 5.71 and 9.78 × 10⁻³ M, respectively.