[Broncholytic effect of prednisolon in the rats inhaled with nitrogen dioxide].

In the rat model of chronic obstructive pulmonary disease, the dilatation effect of prednisolon was most obvious after 15 days of nitrogen dioxide inhalation. In a longer inhalation, the dilatation effect decreases, and on the 90th day of the inhalation prednisolon enhances contraction of the trachea and bronchi. Prednisolon seems to act upon the respiratory tract via interaction with endings of afferent C-fibres. In prolonged inhalation of nitrogen dioxide, resistance against corticosteroids develops as the result of the C-fibre ending inactivation.