Comparative respiratory system mechanics in rodents

• Published in: Journal of applied physiology (1985) Vol. 89; no. 3; pp. 908 - 916
• Main Authors: Gomes, R. F. M, Shen, X, Ramchandani, R, Tepper, R. S, Bates, J. H. T
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01-09-2000; American Physiological Society
• Subjects: Air breathing; Airway Resistance - physiology; Animals; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Guinea Pigs; Mice; Mice, Inbred Strains; Models, Biological; Oxygen; Positive-Pressure Respiration; Rabbits; Rats; Rats, Sprague-Dawley; Respiration, Artificial; Respiratory Mechanics - physiology; Respiratory system; Respiratory system: anatomy, metabolism, gas exchange, ventilatory mechanics, respiratory hemodynamics; Rodentia - physiology; Rodents; Space life sciences; Species Specificity; Ventilation; Vertebrates: respiratory system; Positive end expiratory pressure; Lung volume; Animal model; Vertebrata; Mammalia; Lung function; Forced oscillation; Interspecific comparison; Rodentia; Comparative physiology; Impedance; Respiration
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.2000.89.3.908

1  Meakins-Christie Laboratories, McGill University,
Montreal, Quebec, Canada H2X 2P2; and 2  Department of
Pediatrics, Indiana University School of Medicine, Indianapolis,
Indiana 46223
Because of
the wide utilization of rodents as animal models in respiratory
research and the limited data on measurements of respiratory input
impedance (Zrs) in small animals, we measured Zrs between 0.25 and
9.125 Hz at different levels (0-7 hPa) of positive end-expiratory
pressure (PEEP) in mice, rats, guinea pigs, and rabbits using a
computer-controlled small-animal ventilator (Schuessler TF and Bates
JHT, IEEE Trans Biomed Eng 42: 860-866, 1995).
Zrs was fitted with a model, including a Newtonian resistance (R) and
inertance in series with a constant-phase tissue compartment characterized by tissue damping (Gti) and elastance (Hti) parameters. Inertance was negligible in all cases. R, Gti, and Hti were normalized to body weight, yielding normalized R, Gti, and Hti (NHti),
respectively. Normalized R tended to decrease slightly with PEEP and
increased with animal size. Normalized Gti had a minimal dependence on
PEEP. NHti decreased with increasing PEEP, reaching a minimum at ~5 hPa in all species except mice. NHti was also higher in mice and rabbits compared with guinea pigs and rats at low PEEPs, which we
conclude is probably due to a relatively smaller air space volume in
mice and rabbits. Our data also suggest that smaller rodents have
proportionately wider airways than do larger animals. We conclude
that a detailed, comparative study of respiratory system mechanics
shows some evidence of structural differences among the lungs of
various species but that, in general, rodent lungs obey scaling laws
similar to those described in other species.
respiratory system impedance; forced oscillations; comparative
physiology; small rodents