Length and Curvature of the Dog Diaphragm.
From: Dept. of Medicine, Pulmonary Section, Baylor College of Medicine, Houston, TX 77030, USA. boriek@bcm.tmc.edu
Journal of applied physiology (Bethesda, Md. : 1985)
- Publish Date: Sep 2006
- ISSN: 8750-7587
- Volume: 101
- Issue: 3
- Pages: 794-8
- Medium: Print
- Language: English
- Citation (JAMA): Boriek Aladin M, Black Ben, Hubmayr Rolf, et al. Length and Curvature of the Dog Diaphragm.. J. Appl. Physiol. Sep 2006;101:794-8
Abstract
Transdiaphragmatic pressure is a result of both tension in the muscles of the diaphragm and curvature of the muscles. As lung volume increases, the pressure-generating capability of the diaphragm decreases. Whether decrease in curvature contributes to the loss in transdiaphragmatic pressure and, if so, under what conditions it contributes are unknown. Here we report data on muscle length and curvature in the supine dog. Radiopaque markers were attached along muscle bundles in the midcostal region of the diaphragm in six beagle dogs of approximately 8 kg, and marker locations were obtained from biplanar images at functional residual capacity (FRC), during spontaneous inspiratory efforts against a closed airway at lung volumes from FRC to total lung capacity, and during bilateral maximal phrenic nerve stimulation at the same lung volumes. Muscle length and curvature were obtained from these data. During spontaneous inspiratory efforts, muscle shortened by 15-40% of length at FRC, but curvature remained unchanged. During phrenic nerve stimulation, muscle shortened by 30 to nearly 50%, and, for shortening exceeding 52%, curvature appeared to decrease sharply. We conclude that diaphragm curvature is nearly constant during spontaneous breathing maneuvers in normal animals. However, we speculate that it is possible, if lung compliance were increased and the chest wall and the diameter of the diaphragm ring of insertion were enlarged, as in the case of chronic obstructive pulmonary disease, that decrease in diaphragm curvature could contribute to loss of diaphragm function.
Mesh Headings (Keywords): Animals, Computer Simulation, Diaphragm, Dogs, Models, Anatomic, Models, Biological, Muscle Contraction, Respiratory Mechanics, Supine Position
Check for Full Text / PubMed Unique Identifier (PMID): 16902068
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