Attenuated fatigue in slow twitch skeletal muscle during isotonic exercise in rats with chronic heart failure

Autor: Per Kristian Lunde, Morten Munkvik, Jon Arne Kro Birkeland, Ole M. Sejersted, Ivar Sjaastad, Jan Magnus Aronsen
Jazyk: angličtina
Rok vydání: 2011
Předmět:
Male
Anatomy and Physiology
Muscle Functions
lcsh:Medicine
Isometric exercise
Cardiovascular
Phosphorylation
lcsh:Science
Musculoskeletal System
Multidisciplinary
Physics
Congenital Heart Disease
Muscle Biochemistry
medicine.anatomical_structure
Muscle Fatigue
Cardiology
Muscle
Medicine
End-diastolic volume
medicine.symptom
Physical Laws and Principles
Research Article
Muscle contraction
medicine.medical_specialty
Myosin Light Chains
Mechanics
Muscle Types
Afterload
Isometric Contraction
Physical Conditioning
Animal
Internal medicine
medicine
Animals
Rats
Wistar
Sports and Exercise Medicine
Muscle
Skeletal
Biology
Heart Failure
Muscle fatigue
business.industry
lcsh:R
Skeletal muscle
medicine.disease
Dynamics (Mechanics)
Rats
Surgery
Ventricle
Heart failure
Chronic Disease
lcsh:Q
business
Cardiac Myosins
Zdroj: PLoS ONE, Vol 6, Iss 7, p e22695 (2011)
PLoS ONE
ISSN: 1932-6203
Popis: During isometric contractions, slow twitch soleus muscles (SOL) from rats with chronic heart failure (chf) are more fatigable than those of sham animals. However, a muscle normally shortens during activity and fatigue development is highly task dependent. Therefore, we examined the development of skeletal muscle fatigue during shortening (isotonic) contractions in chf and sham-operated rats. Six weeks following coronary artery ligation, infarcted animals were classified as failing (chf) if left ventricle end diastolic pressure was >15 mmHg. During isoflurane anaesthesia, SOL with intact blood supply was stimulated (1s on 1s off) at 30 Hz for 15 min and allowed to shorten isotonically against a constant afterload. Muscle temperature was maintained at 37°C. In resting muscle, maximum isometric force (F(max)) and the concentrations of ATP and CrP were not different in the two groups. During stimulation, F(max) and the concentrations declined in parallel sham and chf. Fatigue, which was evident as reduced shortening during stimulation, was also not different in the two groups. The isometric force decline was fitted to a bi-exponential decay equation. Both time constants increased transiently and returned to initial values after approximately 200 s of the fatigue protocol. This resulted in a transient rise in baseline tension between stimulations, although this effect which was less prominent in chf than sham. Myosin light chain 2s phosphorylation declined in both groups after 100 s of isotonic contractions, and remained at this level throughout 15 min of stimulation. In spite of higher energy demand during isotonic than isometric contractions, both shortening capacity and rate of isometric force decline were as well or better preserved in fatigued SOL from chf rats than in sham. This observation is in striking contrast to previous reports which have employed isometric contractions to induce fatigue.
Databáze: OpenAIRE
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