Article

A novel method to assess airway function parameters in chronically instrumented, unrestrained guinea-pigs

Department of Pharmacology and Therapeutics, University Centre for Pharmacy, A. Deusinglaan 2, 9713 AW Groningen, The Netherlands; Department of Pulmonology, University Hospital, Oostersingel 59, 9713 EZ Groningen, The Netherlands
Pulmonary Pharmacology DOI:10.1016/0952-0600(92)90069-S pp.265-272

ABSTRACT A new method has been developed to measure airway functions in unanaesthetized, unrestrained guinea-pigs. The technique utilizes a specially designed pneumotachograph that is placed inside the trachea, and a saline-filled balloon, placed inside the pleural cavity. The pneumotachograph consists of a stainless steel cylinder with coaxial and perpendicular tubes attached to it, measuring the total pressure and the lateral pressure in the trachea, respectively. Via air-filled silicon conducting tubes, subcutaneously driven and permanently attached to the neck of the animal, the pressures are fed into a differential pressure transducer, yielding a pressure difference proportional to the airflow in the trachea. Via a saline-filled tubing, the pleural balloon is similarly attached to the neck of the animal, and pleural pressure (Ppl) is measured using a second pressure transducer. These data permit calculation of airway functions in conscious, unstressed animals. Control values for airway resistance (RAW), Ppl, tidal volume and respiratory frequency are all in the range of results reported previously for this species. A very significant correlation between RAW and Ppl (P < 0.001) was observed, indicating that sole Ppl-measurement can be used as a relatively simple and sensitive method to assess bronchial obstructive reactions in unrestrained guinea-pigs. Using a specially designed provocation cage, which allowed the animals to remain in a stress-free, unrestrained condition, the method has been successfully applied for the assessment of the dose-dependent bronchoconstrictor sensitivity to histamine as well as to allergen-induced early and late phase airway reactions. Because chronically instrumented animals can be monitored repeatedly for extended time periods, intra-individual comparisons of airway responses to different pharmacological and immunological stimuli, and to drug treatment, are feasible, while this model may also be suitable for the study of chronic asthma.

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Keywords

chronic asthma
 
chronically instrumented animals
 
Control values
 
designed pneumotachograph
 
designed provocation cage
 
differential pressure transducer
 
dose-dependent bronchoconstrictor sensitivity
 
immunological stimuli
 
new method
 
pleural cavity
 
pleural pressure
 
saline-filled balloon
 
saline-filled tubing
 
second pressure transducer
 
sensitive method
 
stainless steel cylinder
 
tidal volume
 
time periods
 
unrestrained guinea-pigs
 
unstressed animals