Interactive effects of denervation and malnutrition on diaphragm
structure and function.
Lewis, Michael I., Thomas J. Lorusso, Wen-Zhi Zhan, and Gary C. Sieck.
Department of Medicine, Division of Pulmonary/Critical Care
Medicine, The CSMC Burns & Allen Research Institute, Cedars-Sinai
Medical Center, UCLA School of Medicine, Los Angeles, California and
Departments of Anesthesiology and Physiology & Biophysics, Mayo
Clinic, Rochester, Minnesota
APStracts 3:0344A, 1996.
The purpose of this study was to examine the interactive effects of
unilateral denervation (DN) and prolonged malnutrition (MN) on
structure and function of the diaphragm muscle (DIAm). Four groups of
rats were studied: Control (CTL); MN; DN; and DN-MN. MN began two wks
after DN and lasted four wks. In both DN and DN-MN groups, the
relative loss in DIAm weight exceeded the relative change in body
weight. Compared to CTL, DIAm specific force was reduced by 40% in
both DN and DN-MN groups, but was unaffected in the MN animals. DIAm
fatigue resistance improved in all experimental groups, but to a
greater extent in the DN and DN-MN groups. In both DN and DN-MN
animals, 50% of DIAm fibers were classified as type IIc, while fiber
type proportions did not change in the MN group. In DN animals, only
type IIb/x fibers atrophied, whereas all fiber types atrophied in the
MN and DN-MN groups. We conclude that in the DN-MN animals, the
reduction in specific force combined with the reduction in total CSA
of the muscle significantly curtails DIAm force generating capacity.
Received 20 June 1995; accepted in final form 27 June 1996.
APS Manuscript Number A655-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996