Bronchial provocation tests in small animals: a quantified and automated procedure

Area of Science:

• Pharmacology
• Respiratory Physiology
• Animal Models

Background:

• Bronchial provocation tests are crucial for studying airway diseases.
• Standardizing aerosol delivery in laboratory animals is difficult due to unknown drug amounts reaching airways.

Purpose of the Study:

• To design and evaluate an apparatus for improved quantification of aerosolized inhaled stimuli in anesthetized, intubated, and ventilated animals.
• To assess the reproducibility of aerosol delivery and bronchial responsiveness in animal models.

Main Methods:

• Developed a novel apparatus with controlled temperature, hygrometry, computerized pulmonary resistance measurement, and automated aerosol delivery.
• Calibrated aerosol delivery by measuring liquid at the tracheal cannula tip.
• Administered histamine dose-response curves in guinea pigs.

Main Results:

• Despite standardization and automation, aerosol delivery reproducibility was poor (26-42% stroke-by-stroke variation) depending on the nebulizer type (air-jet or ultrasonic).
• Histamine dose-response curves in guinea pigs showed significant inter-animal variability and intra-individual changes in bronchial responsiveness.

Conclusions:

• The developed apparatus did not fully overcome the inherent challenges in standardizing aerosol delivery for bronchial provocation tests in animals.
• Significant variability in both aerosol delivery and animal responses highlights the difficulties in achieving reproducible results in preclinical respiratory research.