Adaptation of respiratory muscle perfusion during exercise to chronically elevated ventilatory work

C. C W Hsia, S. I. Takeda, E. Y. Wu, R. W. Glenny, Jr Johnson R.L.

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

Pneumonectomy (PNX) leads to chronic asymmetric ventilatory loading of respiratory muscles (RM). We measured RM energy requirements during exercise from RM blood flow (Q) using a fluorescent microsphere technique in dogs that had undergone right PNX as adults (adult R-PNX) or as puppies (puppy R-PNX), compared with dogs subjected to right thoracotomy without PNX as puppies (Sham) and to left PNX as adults (adult L-PNX). Ventilatory work (W) was measured during exercise. RM weight was determined post mortem. After adult and puppy R-PNX, the right hemidiaphragm becomes grossly distorted, but W and right costal muscle mass increased only after adult R-PNX. After adult L-PNX, the diaphragm was undistorted; W and left hemidiaphragm RM Q were elevated, but muscle mass did not increase. Mass of parasternal muscle did not increase after adult R-PNX, despite increased Q. Thus muscle mass increased only in response to the combination of chronic stretch and dynamic loading. There was a dorsal-to-ventral gradient of increasing Q within the diaphragm, but the distribution was unaffected by anatomic distortion, hypertrophy, or workload, suggesting a fixed pattern of neural activation. The diaphragm and parasternals were the primary muscles compensating for the asymmetric loading from PNX.

Original languageEnglish (US)
Pages (from-to)1725-1736
Number of pages12
JournalJournal of applied physiology
Volume89
Issue number5
StatePublished - Nov 20 2000

Keywords

  • Diaphragm
  • Dog
  • Microspheres
  • Pneumonectomy
  • Work of breathing

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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