Effect of transpulmonary pressure on airway diameter and responsiveness of immature and mature rabbits

X. Shen, R. Ramchandani, B. Dunn, R. Lambert, S. J. Gunst, R. S. Tepper

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

We previously demonstrated that airway responsiveness is greater in immature than in mature rabbits; however, it is not known whether there are maturational differences in the effect of transpulmonary pressure (Ptp) on airway size and airway responsiveness. The relationship between Ptp and airway diameter was assessed in excised lungs insufflated with tantalum powder. Diameters of comparable intraparenchymal airway segments were measured from radiographs obtained at Ptp between 0 and 20 cmH2O. At Ptp > 8 cmH2O, the diameters were near maximal in both groups. With diameter normalized to its maximal value, changing Ptp between 8 and 0 cmH2O resulted in a greater decline of airway caliber in immature than mature airways. The increases in lung resistance (RL) in vivo at Ptp of 8, 5, and 2 cmH2O were measured during challenge with intravenous methacholine (MCh: 0.001-0.5 mg/kg). At Ptp of 8 cmH2O, both groups had very small responses to MCh and the maximal fold increases in RL did not differ (1.93 ± 0.29 vs. 2.23 ± 0.19). At Ptp of 5 and 2 cmH2O, the fold increases in RL were greater for immature than mature animals (13.19 ± 1.81 vs. 3.89 ± 0.37) and (17.74 ± 2.15 vs. 4.6 ± 0.52), respectively. We conclude that immature rabbits have greater airway distensibility and this difference may contribute to greater airway narrowing in immature compared with mature rabbits.

Original languageEnglish (US)
Pages (from-to)1584-1590
Number of pages7
JournalJournal of Applied Physiology
Volume89
Issue number4
DOIs
StatePublished - 2000

Keywords

  • Maturation

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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