Abstract
Bordetella pertussis vaccination of rats resulted in impairment of relaxation to isoprenaline and histamine of partially contracted tracheal smooth muscle. The concentration range of carbachol (10––6 to 5 × 10––6M) required for contraction (ED50) did not differ from the control group. Pretreatment of vaccinated animals with hydrocortisone was found to reverse the inhibition of spasmolytic activity.