Congestive heart failure: differential adaptation of the diaphragm
and latissimus dorsi.
Howell, Sandra, Jean-Michel I. Maarek, Mario Fournier, Kevin Sullivan,
Wen-Zhi Zhan, Gary C. Sieck.
Departments of Biokinesiology and Physical Therapy and Biomedical
Engineering at the University of Southern California, Los Angeles,
CA; The Division of Pulmonary Medicine at Cedars-Sinai Medical
Center, Los Angeles, CA; and the Departments of Anesthesiology and
Physiology at the Mayo Clinic, Rochester, MN
APStracts 2:0177A, 1995.
Diaphragm and latissimus dorsi muscle function, histochemistry and
morphometry were studied in anesthetized male Yucatan minipigs with
congestive heart failure induced by supraventricular tachycardia
(n=5). Sham-operated animals served as controls (n=5). In CHF
animals, transdiaphragmatic pressure measured during supramaximal
phrenic stimulation was reduced by 40% at low frequencies (/=30 Hz. CSA of
latissimus dorsi type IIb fibers was decreased, but twitch
characteristics, fiber type composition, SDH activity and
fatigability were unchanged. Experimental CHF appears to cause
greater intrinsic adaptive changes in the diaphragm compared with the
latissimus dorsi in the minipig. For both muscles, reduced
contractile function was associated with atrophy. Impaired
performance of the diaphragm also may be attributed to an increase in
the relative contribution of type I fibers to the total tension
-generating capacity of the muscle and to the pathophysiologic
mechanisms underlying the shortened relaxation time of the twitch
response.
Received 16 September 1994; accepted in final form 31 March 1995.
APS Manuscript Number A967-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 2 May 1995.