Although rodents have been widely used in respiratory research, there are still only limited data comparing respiratory mechanics between different species of small animal. In order to provide further insight into the mechanical behavior of the respiratory systems of different sized small animals, accurate measurements of respiratory impedance (Zrs) were made in four different rodent species and in the developing rat over a broad range of frequencies at various levels of positive end-expiratory pressure (PEEP). PEEP dependencies of airway and tissue properties were interpreted in terms of physiological phenomena such as airway closure and airway-parenchymal interdependence forces. In adult animals, Zrs was fitted to a model including a Newtonian resistance (R) in series with a constant-phase tissue compartment. In general, rodent respiratory parameters obeyed the same scaling laws described in other species, but rabbits had a relatively higher elastance than one would predict from previously published allometric relationships. This is probably due to the rabbit's proportionately smaller airspace volume. R normalized to body weight was lower in smaller species suggesting that they have proportionately wider airways compared to larger animals. By using computer models of the asymmetric airway tree to estimate airway resistance (Raw), we confirmed that the larger of two isomorphic rodent species has relatively higher Raw. Moreover, we showed that both the airway dimensional scaling differences and the asymmetric arrangement of the individual airways are responsible for the relative differences in Raw between smaller and larger animals. Finally, in the developing rat, elastance and resistance normalized to lung weight decreased progressively with age, suggesting that intrinsic changes in the mechanical properties of the respiratory system occur with development. Parenchymal interdependence forces manifested themselves in animals as young as 10 days of age, with PEEP
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.38188 |
| Date | January 2001 |
| Creators | Ferreira Matos Gomes, Rute. |
| Contributors | Bates, Jason (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Division of Experimental Medicine.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001864570, proquestno: NQ78685, Theses scanned by UMI/ProQuest. |
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