Separating in vivo mechanical stimuli for postpneumonectomy compensation: Imaging and ultrastructural assessment

Priya Ravikumar, Cuneyt Yilmaz, DenniS J. Bellotto, D. Merrill Dane, Aaron S. Estrera, Connie C W Hsia

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Following right pneumonectomy (PNX), the remaining lung expands and its perfusion more than doubles. Tissue and microvascular mechanical stresses are putative stimuli for compensatory lung growth and remodeling, but their relative contribution remains uncertain. To temporally separate expansionand perfusion-related stimuli, we replaced the right lung of adult dogs with a customized inflated prosthesis. Four months later, the prosthesis was either acutely deflated (DEF) or kept inflated (INF). Thoracic high-resolution computed tomography (HRCT) was performed pre- and post-PNX before and after prosthesis deflation. Lungs were fixed for morphometric analysis ∼12 mo post-PNX. The INF prosthesis prevented mediastinal shift and lateral lung expansion while allowing the remaining lung to expand 27-38% via caudal elongation, associated with reversible capillary congestion in dependent regions at low inflation and 40-60% increases in the volumes of alveolar sepal cells, matrix, and fibers. Delayed prosthesis deflation led to further significant increases in lung volume, alveolar tissue volumes, and alveolar-capillary surface areas. At postmortem, alveolar tissue volumes were 33% higher in the DEF than the INF group. Lateral expansion explains ∼65% of the total post-PNX increase in left lung volume assessed in vivo or ex vivo, ∼36% of the increase in HRCT-derived (tissue + microvascular blood) volume, ∼45% of the increase in ex vivo septal extravascular tissue volume, and 60% of the increase in gas exchange surface areas. This partition agrees with independent physiological measurements obtained in these animals. We conclude that in vivo signals related to lung expansion and perfusion contribute separately and nearly equally to post-PNX growth and remodeling.

Original languageEnglish (US)
Pages (from-to)961-970
Number of pages10
JournalJournal of applied physiology
Volume114
Issue number8
DOIs
StatePublished - Apr 15 2013

Keywords

  • Compensatory lung growth
  • High-resolution computed tomography
  • Lung resection
  • Mechanical deformation
  • Morphometry

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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