Effects of moderate heart failure and functional overload on rat plantaris muscle

2002 ◽  
Vol 92 (1) ◽  
pp. 18-24 ◽  
Author(s):  
Espen E. Spangenburg ◽  
Simon J. Lees ◽  
Jeff S. Otis ◽  
Timothy I. Musch ◽  
Robert J. Talmadge ◽  
...  

It is thought that changes in sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) of skeletal muscle contribute to alterations in skeletal muscle function during congestive heart failure (CHF). It is well established that exercise training can improve muscle function. However, it is unclear whether similar adaptations will result from exercise training in a CHF patient. Therefore, the purpose of this study was to determine whether skeletal muscle during moderate CHF adapts to increased activity, utilizing the functional overload (FO) model. Significant increases in plantaris mass of the CHF-FO and sham-FO groups compared with the CHF and control (sham) groups were observed. Ca2+ uptake rates were significantly elevated in the CHF group compared with all other groups. No differences were detected in Ca2+ uptake rates between the CHF-FO, sham, and sham-FO groups. Increases in Ca2+ uptake rates in moderate-CHF rats were not due to changes in SERCA isoform proportions; however, FO may have attenuated the CHF-induced increases through alterations in SERCA isoform expression. Therefore, changes in skeletal muscle Ca2+handling during moderate CHF may be due to alterations in regulatory mechanisms, which exercise may override, by possibly altering SERCA isoform expression.

2003 ◽  
Vol 94 (6) ◽  
pp. 2225-2236 ◽  
Author(s):  
Bryan Helwig ◽  
Katherine M. Schreurs ◽  
Joslyn Hansen ◽  
K. Sue Hageman ◽  
Michael G. Zbreski ◽  
...  

The mechanisms responsible for the decrements in exercise performance in chronic heart failure (CHF) remain poorly understood, but it has been suggested that sarcolemmal alterations could contribute to the early onset of muscular fatigue. Previously, our laboratory demonstrated that the maximal number of ouabain binding sites (Bmax) is reduced in the skeletal muscle of rats with CHF (Musch TI, Wolfram S, Hageman KS, and Pickar JG. J Appl Physiol 92: 2326–2334, 2002). These reductions may coincide with changes in the Na+-K+-ATPase isoform (α and β) expression. In the present study, we tested the hypothesis that reductions in Bmax would coincide with alterations in the α- and β-subunit expression of the sarcolemmal Na+-K+-ATPase of rats with CHF. Moreover, we tested the hypothesis that exercise training would increase Bmax along with producing significant changes in α- and β-subunit expression. Rats underwent a sham operation (sham; n = 10) or a surgically induced myocardial infarction followed by random assignment to either a control (MI; n = 16) or exercise training group (MI-T; n = 16). The MI-T rats performed exercise training (ET) for 6–8 wk. Hemodynamic indexes demonstrated that MI and MI-T rats suffered from severe left ventricular dysfunction and congestive CHF. Maximal oxygen uptake (V˙o 2 max) and endurance capacity (run time to fatigue) were reduced in MI rats compared with sham. Bmax in the soleus and plantaris muscles and the expression of the α2-isoform of the Na+-K+-ATPase in the red portion of the gastrocnemius (gastrocnemiusred) muscle were reduced in MI rats. After ET, V˙o 2 max and run time to fatigue were increased in the MI-T group of rats. This coincided with increases in soleus and plantaris Bmax and the expression of the α2-isoform in the gastrocnemiusred muscle. In addition, the expression of the β2-isoform of the gastrocnemiusred muscle was increased in the MI-T rats compared with their sedentary counterparts. This study demonstrates that CHF-induced alterations in skeletal muscle Na+-K+-ATPase, including Bmax and isoform expression, can be partially reversed by ET.


2010 ◽  
Vol 109 (3) ◽  
pp. 702-709 ◽  
Author(s):  
C. R. Bueno ◽  
J. C. B. Ferreira ◽  
M. G. Pereira ◽  
A. V. N. Bacurau ◽  
P. C. Brum

The cellular mechanisms of positive effects associated with aerobic exercise training on overall intrinsic skeletal muscle changes in heart failure (HF) remain unclear. We investigated potential Ca2+ abnormalities in skeletal muscles comprising different fiber compositions and investigated whether aerobic exercise training would improve muscle function in a genetic model of sympathetic hyperactivity-induced HF. A cohort of male 5-mo-old wild-type (WT) and congenic α2A/α2C adrenoceptor knockout (ARKO) mice in a C57BL/6J genetic background were randomly assigned into untrained and trained groups. Exercise training consisted of a 8-wk running session of 60 min, 5 days/wk (from 5 to 7 mo of age). After completion of the exercise training protocol, exercise tolerance was determined by graded treadmill exercise test, muscle function test by Rotarod, ambulation and resistance to inclination tests, cardiac function by echocardiography, and Ca2+ handling-related protein expression by Western blot. α2A/α2CARKO mice displayed decreased ventricular function, exercise intolerance, and muscle weakness paralleled by decreased expression of sarcoplasmic Ca2+ release-related proteins [α1-, α2-, and β1-subunits of dihydropyridine receptor (DHPR) and ryanodine receptor (RyR)] and Ca2+ reuptake-related proteins [sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA)1/2 and Na+/Ca2+ exchanger (NCX)] in soleus and plantaris. Aerobic exercise training significantly improved exercise tolerance and muscle function and reestablished the expression of proteins involved in sarcoplasmic Ca2+ handling toward WT levels. We provide evidence that Ca2+ handling-related protein expression is decreased in this HF model and that exercise training improves skeletal muscle function associated with changes in the net balance of skeletal muscle Ca2+ handling proteins.


1997 ◽  
Vol 18 (10) ◽  
pp. 1626-1631 ◽  
Author(s):  
C. Opasich ◽  
E. Pasini ◽  
R. Aquilani ◽  
F. Coelli ◽  
R. Solfrini ◽  
...  

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