Comparison between Penh and airway resistance in a mild and severe mouse model for allergic asthma

Background: For many years the parameter Penh to measure airway hyperresponsiveness has been under discussion. Objective: Compare invasive ventilated lung resistance in anesthetized mice with the non-invasive non-ventilated Penh measurement in conscious mice in a mild and severe allergic asthma model. Methods: In Balb/c mice airway hyperresponsiveness and inflammation were determined. Intraperitoneal sensitization and aerosol of ovalbumine was used to induce mild asthma. Intraperitoneal sensitization with trinitrophenyl-ovalbumin followed by intranasal challenge with trinitrophenyl-ovalbumin-IgE was used to induce severe asthma. One hour after lung function measurement bronchoalveolar lavage was performed. Results: A significant increase in airway responsiveness to methacholine was observed in the mild group when lung resistance was measured but not with the Penh. The increased airway responsiveness was much more pronounced in the severe group and significant changes were observed using lung resistance measurement or Penh. In the mild group there was a significant increase in number of inflammatory cells in the bronchoalveolar lavage which was more pronounced in the severe group. Interestingly, ventilation of the animals after the lung resistance measurement, increased even further the number of cells in the bronchoalveolar lavage. Conclusion: Although the Penh is under discussion, it seems that ventilation of the animals increases the numbers of bronchoalveolar lavage cells independent of the severity of asthma. The acute increase of inflammatory cells due to ventilation, may contribute to the more pronounced increase in airway responsiveness using the lung resistance measurement.