Effects of inactivity on human muscle glutathione synthesis by a double-tracer and single-biopsy approach.

Oxidative stress is often associated to inactivity-mediated skeletal muscle atrophy. Glutathione is one of the major antioxidant systems stimulated, both at muscular and systemic level, by activation of oxidative processes. We measured changes in glutathione availability, oxidative stress induction and the extent of atrophy mediated by 35 days of experimental bed rest in vastus lateralis muscle of healthy human volunteers. To assess muscle glutathione synthesis, we applied a novel single-biopsy and double-tracer ([(2)H(2)]glycine and [(15)N]glycine) approach based on evaluation of steady-state precursor incorporation in product. The correlations between the traditional (multiple-samples, one-tracer) and new (one-sample, double-tracer infusion) methods were analysed in erythrocytes by Passing-Bablok and Altman-Bland tests. Muscle glutathione absolute synthesis rate increased following bed rest from 5.5 ± 1.1 to 11.0 ± 1.5 mmol (kg wet tissue)(-1) day(-1) (mean ± S.E.M.; n = 9; P = 0.02) while glutathione concentration failed to change significantly. Bed rest induced vastus lateralis muscle atrophy, as assessed by pennation angle changes measured by ultrasonography (from 18.6 ± 1.0 to 15.3 ± 0.9 deg; P = 0.01) and thickness changes (from 2.3 ± 0.2 to 1.9 ± 0.1 cm; P < 0.001). Moreover, bed rest increased protein oxidative stress, as measured by muscle protein carbonylation changes (from 0.6 ± 0.1 to 1.00 ± 0.1 Oxydized-to-total protein ratio; P < 0.04). In conclusion, we developed in erythrocytes a new minimally invasive method to determine peptide synthesis rate in human tissues. Application of the new method to skeletal muscle suggests that disuse atrophy is associated to oxidative stress induction as well as to compensatory activation of the glutathione system.

Exercise intolerance in chronic heart failure: mechanisms and therapies. Part I.

Muscular fatigue and dyspnoea on exertion are among the most common symptoms in chronic heart failure; however their origin is still poorly understood. Several studies have shown that cardiac dysfunction alone cannot fully explain their origin, but the contribution of the multiorgan failure present in this syndrome must be highlighted. In this study, divided in two parts (see part II: pp. 643­648), we aimed to summarize the existing evidence and the most controversial aspects of the complex interplay of different factors involved in symptom generation. In this first part of the review, six key factors are revised: the heart, the lung, the skeletal muscle, the hormonal changes, the O2 delivery to the periphery, the endothelium. In the second part, the role of the excitatory reflexes and the cardiac cachexia will be presented, and finally, the potential therapeutic implications are discussed. We believe that a better knowledge of the pathophysiology of this syndrome may contribute to the management of the patients and to the improvement in their stress tolerance and quality of life.

Exercise intolerance in chronic heart failure: mechanisms and therapies. Part II.

Muscular fatigue and dyspnoea on exertion are among the most common symptoms in chronic heart failure; however their origin is still poorly understood. Several studies have shown that cardiac dysfunction alone cannot fully explain their origin, but the contribution of the multiorgan failure present in this syndrome must be highlighted. We aimed to summarize the existing evidence and the most controversial aspects of the complex interplay of different factors involved in the symptom generation. In the first part of the review, six key factors were revised (the heart, the lung, the skeletal muscle, the hormonal changes, the O2 delivery to the periphery, the endothelium). In this second part, the role of the excitatory reflexes and the cardiac cachexia are presented. Finally, potential therapeutic implications are discussed here. We believe that a better knowledge of the pathophysiology of this syndrome may contribute to the management of the patients and to the improvement in their stress tolerance and quality of life.

Skeletal muscle proteins oxidation in chronic right heart failure in rats: can different beta-blockers prevent it to the same degree?

BACKGROUND: Skeletal muscle atrophy and decreased expression of slow fibers contribute to exercise capacity limitation in Chronic Heart Failure (CHF). Pro-inflammatory cytokines and free radicals worsen muscle damage. In CHF sarcomeric proteins are oxidized with reduction of muscle twitch efficiency, and VO(2)-max. Beta-blockers with anti-oxidative capacity such as carvedilol have been shown to prevent contractile protein oxidation in CHF rats. Recently a new class of beta-blockers with NO donor activity has been introduced and approved for the treatment of CHF. Since a clinical clear superiority of a beta-blocker has never been shown, we compared nebivolol, that possesses NO donor activity, with bisoprolol, looking at possible differences in skeletal muscle that may have an impact on muscle function and exercise capacity in humans. We therefore studied skeletal muscle apoptosis and wastage, sarcomeric protein composition and oxidation, and muscle efficiency. METHODS AND RESULTS: In the monocrotaline rat model of CHF we compared nebivolol a beta-blocker with vasodilative properties mediated by NO production, with bisoprolol. Nebivolol prevented protein oxidation, while bisoprolol did it only partially, as demonstrated by the oxyblot analysis (Oxy/RP values) (0.90+/-0.14 Controls.; 1.7+/-0.14 CHF; 1.1+/-0.05 bisoprolol; 0.82+/-0.17 nebivolol low; 0.62+/-0.10 nebivolol high). Only nebivolol improved twitch force production and relaxation. Nebivolol prevented fibers shift towards fast isoforms, atrophy, decreased apoptosis and sphingosine levels. CONCLUSIONS: Nebivolol seems better than bisoprolol in CHF by decreasing apoptosis and cytokines induced muscle wastage, preventing fibers shift and protein oxidation. Nebivolol by stimulating NO generation may have prevented protein oxidation. It could be speculated that ROS release, pro-inflammatory cytokines production and NF-kappa-B activation may play a key role. These positive changes could produce a favorable impact on exercise capacity in man.

A transient antioxidant stress response accompanies the onset of disuse atrophy in human skeletal muscle.

It is presently unknown whether oxidative stress increases in disused skeletal muscle in humans. Markers of oxidative stress were investigated in biopsies from the vastus lateralis muscle, collected from healthy subjects before [time 0 (T0)], after 1 wk (T8), and after 5 wk (T35) of bed rest. An 18% decrease in fiber cross-sectional area was detected in T35 biopsies (P<0.05). Carbonylation of muscle proteins significantly increased about twofold at T35 (P<0.02) and correlated positively with the decrease in fiber cross-sectional area (P=0.04). Conversely, T8 biopsies showed a significant increase in protein levels of heme oxygenase-1 and glucose-regulated protein-75 (Grp75)/mitochondrial heat shock protein-70, two stress proteins involved in the antioxidant defense (P<0.05). Heme oxygenase-1 increase, which involved a larger proportion of slow fibers compared with T0, appeared blunted in T35 biopsies. Grp75 protein level increased threefold in T8 biopsies and localized especially in slow fibers (P<0.025), to decrease significantly in T35 biopsies (P<0.05). Percent change in Grp75 levels positively correlated with fiber cross-sectional area (P=0.01). Parallel investigations on rat soleus muscles, performed after 1-15 days of hindlimb suspension, showed that Grp75 protein levels significantly increased after 24 h of unloading (P = 0.02), i.e., before statistically significant evidence of muscle atrophy, to decrease thereafter in relation to the degree of muscle atrophy (P=0.03). Therefore, in humans as in rodents, disuse muscle atrophy is characterized by increased protein carbonylation and by the blunting of the antioxidant stress response evoked by disuse.

Physiological basis for contractile dysfunction in heart failure.

The purpose of this review is to enlighten the mechanisms of skeletal muscle dysfunction in heart failure. The muscle hypothesis suggests that chronic heart failure (CHF) symptoms, dyspnoea and fatigue are due to skeletal muscle alterations. Hyperventilation due to altered ergoreflex seems to be the cause of shortness of breath. Qualitative and quantitative changes occurring in the skeletal muscle, such as muscle wastage and shift from slow to fast fibers type, are likely to be responsible for fatigue. Mechanisms leading to muscle wastage in chronic heart failure, include cytokine-triggered skeletal muscle apoptosis, but also ubiquitin/proteasome and non-ubiquitin-dependent pathways. The regulation of fibre type involves the growth hormone/insulin-like growth factor 1/calcineurin/ transcriptional coactivator PGC1 cascade. The imbalance between protein synthesis and degradation plays an important role. Protein degradation can occur through ubiquitin-dependent and non-ubiquit-independent pathways. Systems controlling ubiquitin/ proteasome activation have been described. These are triggered by tumour necrosis factor and growth hormone/ insulin-like growth factor 1. However, an important role is played by apoptosis. In humans, and experimental models of heart failure, programmed cell death has been found in skeletal muscle and interstitial cells. Apoptosis is triggered by tumour necrosis factor and in vitro experiments have shown that it can be induced by its second messenger sphingosine. Apoptosis correlates with the severity of the heart failure syndrome. It involves activation of caspases 3 and 9 and mitochondrial cytochrome c release. Sarcomeric protein oxidation and its consequent contractile impairment can form another cause of skeletal muscle dysfunction in CHF.

Trophic action of sphingosine 1-phosphate in denervated rat soleus muscle.

Sphingosine 1-phosphate (S1P) mediates a number of cellular responses, including growth and proliferation. Skeletal muscle possesses the full enzymatic machinery to generate S1P and expresses the transcripts of S1P receptors. The aim of this work was to localize S1P receptors in rat skeletal muscle and to investigate whether S1P exerts a trophic action on muscle fibers. RT-PCR and Western blot analyses demonstrated the expression of S1P(1) and S1P(3) receptors by soleus muscle. Immunofluorescence revealed that S1P(1) and S1P(3) receptors are localized at the cell membrane of muscle fibers and in the T-tubule membranes. The receptors also decorate the nuclear membrane. S1P(1) receptors were also present at the neuromuscular junction. The possible trophic action of S1P was investigated by utilizing the denervation atrophy model. Rat soleus muscle was analyzed 7 and 14 days after motor nerve cut. During denervation, S1P was continuously delivered to the muscle through a mini osmotic pump. S1P and its precursor, sphingosine (Sph), significantly attenuated the progress of denervation-induced muscle atrophy. The trophic effect of Sph was prevented by N,N-dimethylsphingosine, an inhibitor of Sph kinase, the enzyme that converts Sph into S1P. Neutralization of circulating S1P by a specific antibody further demonstrated that S1P was responsible for the trophic effects of S1P during denervation atrophy. Denervation produced the down regulation of S1P(1) and S1P(3) receptors, regardless of the presence of the receptor agonist. In conclusion, the results suggest that S1P acts as a trophic factor of skeletal muscle.

Skeletal muscle myofibrillar protein oxidation and exercise capacity in heart failure.

BACKGROUND: Heart failure is characterized by limited exercise tolerance and by a skeletal muscle myopathy with atrophy and shift toward fast fibres. An inflammatory status with elevated pro-inflammatory cytokines and exaggerated free radicals production can worsen muscle damage. We have previously demonstrated in a model of heart failure, the monocrotaline treated rat, that oxidation of skeletal muscle actin, tropomyosin and myosin produces a reduction of contractile efficiency, which may further depress muscle function and exercise capacity. AIMS: To investigate the presence of oxidized myofibrillar proteins in skeletal muscle of CHF patients by means of the Oxyblot technique and to correlate it with exercise capacity. METHODS: We have analyzed skeletal muscle biopsies taken from six patients with class III-IV NYHA CHF and four control patients (peak VO(2) 12.8 +/- 1.9 vs. 29.7 +/- 1.7 ml/kg/min, p < 0.0001). RESULTS AND CONCLUSIONS: A correlation between degree of myofibrillar oxidation and exercise capacity measured as peak VO(2) was obtained. In the skeletal muscle of CHF patient there was a much higher level of myofibrillar protein oxidation as expressed by the Oxyblot/Red Ponceau (Oxy/RP) ratio as compared to controls (2.1 +/- 0.3 vs. 1.02 +/- 0.09, p < 0.0001). The VO(2)/Oxy/RP was significantly lower in the CHF patients. Higher levels of muscle oxidation were found in patients with lower exercise capacity with an inverse correlation between Oxyblot and VO(2) values (r (2) = 0.83).

Carnitine-mediated improved response to erythropoietin involves induction of haem oxygenase-1: studies in humans and in an animal model.

BACKGROUND: Carnitine improves erythropoetin (EPO) response and anaemia in haemodialysis patients (HD); however, the mechanism(s) responsible remain unidentified. We have reported that carnitine induces haem oxygenase (HO)-1, which is an antioxidant and antiapoptotic that acts via pathways shared with EPO. Therefore carnitine's effect on these pathways may account for the improved EPO response. This study evaluates carnitine's effect on protein expression of HO-1 in unexplained EPO resistant HD. Carnitine's effect was assessed by HO-1 expression in patients and compared to its antiapoptotic effect via HO-1 induction in a rat model of carnitine-treated heart failure. METHODS: Unexplained EPO resistant HD mononuclear cell HO-1 and rat gastrocnemious muscle HO-1 and Bcl-2 protein expression were evaluated by western blot. RESULTS: HD's haemoglobin (Hb) and haematocrit (Ht) were not different before carnitine treatment: 8.8 +/- 0.4 mg/dl versus 8.98 +/- 0.13 and 30.20% +/- 0.84 versus 30.72 +/- 1.14, respectively. Carnitine increased HO-1, Hb and Ht compared with patients not treated with carnitine: 2.40 +/- 0.58 versus 1.49 +/- 0.41, P = 0.02; 11.22 +/- 0.54 versus 8.90 +/- 0.15, P < 0.0001; 32.72 +/- 1.77 versus 30.66 +/- 0.43, P = 0.035, respectively. Carnitine-treated HD's HO-1 significantly correlated with haemoglobin. HO-1 and Bcl-2 protein levels in untreated heart failure rat's gastrocnemious muscle were reduced when compared with controls: 3.41 +/- 0.49 versus 5.32 +/- 0.38 and 0.69 +/- 0.11 versus 1.65 +/- 0.37, respectively, but were higher in carnitine-treated heart failure rats: 4.8 +/- 0.32 versus 3.41 +/- 0.49, P < 0.0002 and 1.09 +/- 0.08 versus 0.69 +/- 0.11, P = 0.0007, respectively. CONCLUSIONS: These results are consistent with an involvement of HO-1 in carnitine's effect on erythropoiesis. The initial signals or effectors responsible for carnitine's effect remain to be identified.

Skeletal muscle wastage in Crohn's disease: a pathway shared with heart failure?

BACKGROUND: Lean body mass wastage in active Crohn's disease is not only related to malnutrition, but also to local and systemic inflammation. Altered bowel permeability can represent a source of pro-inflammatory cytokines, that have been shown to produce muscle wastage by several mechanisms such as apoptosis. In our study we have evaluated the body composition and the pathological changes of skeletal muscle in patients with Crohn's disease to see whether a relationships between altered gut permeability, proinflammatory cytokines production and muscle wastage existed. METHODS: Thirteen consecutive steroid-free patients with active Crohn's disease underwent evaluation of body composition, sugar test for intestinal permeability, determination of serum levels of TNF-alpha, sphingosine, bacterial lipopolysaccaride, and biopsy of gastrocnemius. In bioptic samples we determined fibres cross sectional area, distribution of myosin heavy chains and apoptosis. Twenty healthy subjects formed the control group. RESULTS: In patients lean body mass was reduced and intestinal permeability increased (p<0.01 for both). TNFalpha, sphingosine and lipopolysaccaride were increased (p<0.01). Fibres size was reduced (p<0.01), with shift of Myosin Heavy Chains from the slow to the fast type. Apoptosis was found in 5 patients' biopsies, never in controls. CONCLUSIONS: Crohn's patients have a myopathy characterized by myocyte apoptosis, modifications of myosin and muscle atrophy. TNF-alpha and sphingosine, that are increased because of the enhanced lipopolysaccaride concentration due to altered gut permeability, may play a pathophysiological role in the development of this myopathy.

Skeletal muscle apoptosis in experimental heart failure: the only link between inflammation and skeletal muscle wastage?

PURPOSE OF REVIEW: The purpose of this review is to enlighten the mechanisms of muscle wastage in experimental heart failure with attention to skeletal muscle apoptosis and the role of proinflammatory cytokines that trigger apoptosis. RECENT FINDINGS: Mechanisms leading to muscle wastage in chronic heart failure include cytokine-triggered skeletal muscle apoptosis, but also ubiquitin/proteasome and non-ubiquitin-dependent pathways. The regulation of fibre type involves the growth hormone/insulin-like growth factor 1/calcineurin/transcriptional coactivator PGC1 cascade. SUMMARY: Several mechanisms can lead to muscle wastage in heart failure. The imbalance between protein synthesis and degradation plays an important role. Protein degradation can occur through ubiquitin-dependent and non-ubiquitin-dependent pathways. Systems controlling ubiquitin/proteasome activation have been described. These are triggered by tumour necrosis factor alpha and growth hormone/insulin-like growth factor 1. However, an important role is played by apoptosis. In humans and experimental models of heart failure programmed cell death has been found in skeletal muscle and interstitial cells. Apoptosis is triggered by tumour necrosis factor alpha and in-vitro experiments have shown that it can be induced by its second messenger sphingosine. Apoptosis correlates with the severity of the heart failure syndrome. It involves activation of caspases 3 and 9 and mitochondrial cytochrome c release.

Inflammation and perturbation of the l-carnitine system in heart failure.

BACKGROUND: Heart failure (HF) is accompanied by elevated levels of pro-inflammatory cytokines. Skeletal muscle myopathy with atrophy of fibres, decreased oxidative metabolism and preferential synthesis of fast myosin heavy chains (MHCs) occurs, which contributes to the worsening of symptoms. l-Carnitine has been shown to be protective against the apoptosis-induced atrophy of fibres and fast MHCs shift. AIMS: To investigate the interrelationship between TNFalpha and sphingosine (SPH), which induce muscle wastage, and plasma levels of l-carnitine. METHODS: We studied 18 heart failure patients and correlated NYHA class and ventricular function with the plasma concentration of these molecules. RESULTS: TNFalpha and SPH levels were raised and correlated with the severity of HF. l-Carnitine levels were increased in HF patients, but decreased according to the severity of cardiac decompensation. CONCLUSIONS: The increased levels of l-carnitine are likely due to release from the damaged muscle, reduced urinary excretion, decreased dietary intake and liver synthesis (malnutrition). It is possible that the cytokine-induced muscle wastage is not counterbalanced by the beneficial metabolic effects of l-carnitine, the metabolism of which is profoundly perturbed in CHF. l-Carnitine supplementation may produce positive effects on the skeletal muscle, as has been shown in animal models of HF.

Skeletal muscle fibres synthesis in heart failure: role of PGC-1alpha, calcineurin and GH.

BACKGROUND: Patients with congestive heart failure (CHF) have decreased exercise capacity because of muscle fatigability. Symptoms are due to a specific myopathy with increased expression of fast type II fibres, fast MHCs and muscle atrophy. PGC-1alpha, a potent transcriptional coactivator for nuclear receptors, induces mitochondrial myogenesis and the preferential synthesis of slow fibres. IGF1-Calcineurin stimulation can lead to increased expression of PGC-1alpha. METHODS: We investigated the levels of PGC-1alpha during progression and regression of skeletal myopathy in the soleus muscle of rats with right heart failure secondary to monocrotaline-induced pulmonary hypertension. We used GH to stimulate the IGF1-calcineurin-PGC-1alpha axis. RESULTS: The slow MHC1 decreased from 90.6+/-0.5 to 71.7+/-2.2 in the CHF rats (p<0.00001) and increased to 82.1+/-1.8 after GH (p<0.00002). Western blot analysis showed that PGC-1alpha is significantly decreased in CHF, while it came back to control values after GH. Cytochrome c was decreased in CHF and returned to control values with GH. Troponin I was expressed solely as slow isoform in the control soleus, while the fast isoform appeared in CHF. Its expression returned to control values after GH. CONCLUSIONS: We conclude that PGC-1alpha plays an important role in regulating slow fibres expression. PGC1-1alpha is in turn regulated by the IGF1-calcineurin axis. GH by increasing the circulating levels of IGF1, enhanced the expression of slow MHC1, TnI and the synthesis of mitochondria.

Skeletal muscle myofibrillar protein oxidation in heart failure and the protective effect of Carvedilol.

Heart failure is characterized by limited exercise tolerance and by a skeletal muscle myopathy with atrophy and shift toward fast fibres. An inflammatory status with elevated pro-inflammatory cytokines and exaggerated free radicals production, can worsen muscle damage. In a well established model of heart failure, the monocrotaline treated rat, we show that CHF is accompanied by oxidation of the skeletal muscle actin, tropomyosin and myosin, which further depresses muscle function and exercise capacity. We have also tested the efficacy of Carvedilol, a non-selective beta(1)-beta(2)-blocker, which has been widely used in clinical trials to improve exercise tolerance and reduce mortality in moderate and severe CHF, in preventing contractile protein oxidation in CHF rats. As comparison we used Bisoprolol a beta(1) selective agent, without known anti-oxidative properties. Carvedilol at the dose of 2 mg/kg per day was able to prevent the myofibrillar protein oxidation, while Bisoprolol (0.1 mg/kg) did it only partially, as demonstrated by the oxyblot analysis. While Carvedilol improved force production on isolated muscles, Bisoprolol did not. After the COMET trial, the anti-oxidative capacity of Carvedilol has been invoked as one of the mechanism that makes this drug superior to other selective beta-blockers in the treatment of CHF. One of the reason of Carvedilol superiority could be the effect on skeletal muscle with reduction of contractile protein peroxidation, amelioration of muscle function and improvement of exercise tolerance. Inhibition of reactive oxygen species (ROS) production, and of pro-inflammatory cytokines may also lead to a decreased muscle wastage, another factor contributing to worsening of exercise tolerance.

Beneficial effects of GH/IGF-1 on skeletal muscle atrophy and function in experimental heart failure.

Muscle atrophy is a determinant of exercise capacity in heart failure (CHF). Myocyte apoptosis, triggered by tumor necrosis factor-alpha (TNF-alpha) or its second messenger sphingosine (SPH), is one of the causes of atrophy. Growth hormone (GH) improves hemodynamic and cardiac trophism in several experimental models of CHF, but its effect on skeletal muscle in CHF is not yet clear. We tested the hypothesis that GH can prevent skeletal muscle apoptosis in rats with CHF. CHF was induced by injecting monocrotaline. After 2 wk, 2 groups of rats were treated with GH (0.2 mg.kg(-1).day(-1) and 1.0 mg.kg(-1).day(-1)) subcutaneously. A third group of controls had saline. After 2 additional weeks, rats were killed. Tibialis anterior cross-sectional area, myosin heavy chain (MHC) composition, and a study on myocyte apoptosis and serum levels of TNF-alpha and SPH were carried out. The number of apoptotic nuclei, muscle atrophy, and serum levels of TNF-alpha and SPH were decreased with GH at high but not at low doses compared with CHF rats. Bcl-2 was increased, whereas activated caspases and bax were decreased. The MHC pattern in GH-treated animals was similar to that of controls. Monocrotaline slowed down both contraction and relaxation but did not affect specific tetanic force, whereas absolute force was decreased. GH treatment restored contraction and relaxation to control values and brought muscle mass and absolute twitch and tetanic tension to normal levels. These findings may provide an insight into the therapeutic strategy of GH given to patients with CHF to improve exercise capacity.

Skeletal muscle abnormalities in rats with experimentally induced heart hypertrophy and failure.

BACKGROUND: In congestive heart failure (CHF), function and metabolism of skeletal muscles are abnormal. AIM: To evaluate whether the reduced oxidative capacity of skeletal muscles in CHF is due to impaired O(2) utilisation. METHODS: CHF was induced in rats by injecting 50 mg/Kg monocrotaline. Several animals received the same dose of monocrotaline but only compensated right ventricular hypertrophy and no sign of congestion resulted. Two age- and diet-matched groups of control animals were also studied. In soleus and extensor digitorum longus (EDL) muscles, we studied skeletal muscle blood flow, oxidative capacity and respiratory function of skinned muscle fibres. RESULTS: In CHF, we observed a decrease of muscle blood flow (statistically significant in the soleus, p < 0.05 vs. controls). In compensated rats, a similar trend in blood flow was observed. In both soleus and EDL, a significant reduction of high energy phosphate and a shift of the redox potential towards accumulation of reducing equivalents were observed. The reduction of energy charge was not correlated to the decrease of blood flow. In skinned myofibres, the ratio of O(2) utilised in the presence and in absence of ADP (an index of phoshorilating efficiency) was reduced from 8.9 +/- 1.9 to 2.7 +/- 0.2 (p < 0.001) and from 5.7 +/- 1.0 to 2.0 +/- 0.3 (p < 0.01) in soleus and EDL, respectively. Activity of the different complexes of respiratory chain was investigated by means of specific inhibitors, showing major abnormalities at the level of complex I. In fact, inhibition of VO(2) by rotenone was decreased from 83.5 +/- 3.2 to 36.4 +/- 9.6 % (p < 0.005) and from 81.8 +/- 6.1 to 38.2 +/- 7.4 % (p < 0.005) in soleus and EDL, respectively. CONCLUSIONS: In rats with CHF, abnormalities of oxidative phosphorylation of muscles occur and complex I of the respiratory chain seem to be primarily affected. The metabolic alterations of skeletal muscles in CHF may be explained, at least in part, by an impaired O(2) utilisation.

Effect of thalidomide on the skeletal muscle in experimental heart failure.

BACKGROUND: Tumour Necrosis Factor alpha (TNFalpha) has been shown to contribute to heart failure (CHF) progression. AIMS: We have tried to antagonise the detrimental effects of TNFalpha on skeletal muscle apoptosis, by using thalidomide, a drug that inhibits its biosynthesis. METHODS: CHF was induced in 20 rats by injecting monocrotaline, which determines right ventricle (RV) failure. After 2 weeks, when CHF developed, 12 rats were treated with thalidomide 3.5.mg/kg per day for 2 weeks. Eight had saline and served as CHF controls. RESULTS: Thalidomide failed to decrease TNFalpha and its second messenger sphingosine (SPH), but was able to prevent the shift toward the fast myosin heavy chains. In the Tibialis Anterior muscle of the thalidomide group, the degree of atrophy, the number of apoptotic nuclei and the levels of caspases, were similar to those of the CHF controls. CONCLUSIONS: Thalidomide, at the doses used in this study, which are the same employed for the treatment of tubercolosis, leprosy, AIDS and cancer in humans, did not lower either TNFalpha or SPH and only marginally influenced the apoptosis-induced muscle atrophy. Since other TNFalpha blockers are under investigation for improving the clinical status of patients with CHF, the present data could be relevant in the design of randomised clinical trials in humans.

L-Carnitine: a potential treatment for blocking apoptosis and preventing skeletal muscle myopathy in heart failure.

Skeletal muscle in congestive heart failure is responsible for increased fatigability and decreased exercise capacity. A specific myopathy with increased expression of fast-type myosins, myocyte atrophy, secondary to myocyte apoptosis triggered by high levels of circulating tumor necrosis factor-alpha (TNF-alpha) has been described. In an animal model of heart failure, the monocrotaline-treated rat, we have observed an increase of apoptotic skeletal muscle nuclei. Proapoptotic agents, caspase-3 and -9, were increased, as well as serum levels of TNF-alpha and its second messenger sphingosine. Treatment of rats with L-carnitine, known for its protective effect on muscle metabolism injuries, was found to inhibit caspases and to decrease the levels of TNF-alpha and sphingosine, as well as the number of apoptotic myonuclei. Staurosporine was used in in vitro experiments to induce apoptosis in skeletal muscle cells in culture. When L-carnitine was applied to skeletal muscle cells, before staurosporine treatment, we observed a reduction in apoptosis. These findings show that L-carnitine can prevent apoptosis of skeletal muscles cells and has a role in the treatment of congestive heart failure-associated myopathy.

Effect of thalidomide on the skeletal muscle in experimental heart failure

BACKGROUND: Tumour Necrosis Factor alpha (TNFalpha) has been shown to contribute to heart failure (CHF) progression. AIMS: We have tried to antagonise the detrimental effects of TNFalpha on skeletal muscle apoptosis, by using thalidomide, a drug that inhibits its biosynthesis. METHODS: CHF was induced in 20 rats by injecting monocrotaline, which determines right ventricle (RV) failure. After 2 weeks, when CHF developed, 12 rats were treated with thalidomide 3.5.mg/kg per day for 2 weeks. Eight had saline and served as CHF controls. RESULTS: Thalidomide failed to decrease TNFalpha and its second messenger sphingosine (SPH), but was able to prevent the shift toward the fast myosin heavy chains. In the Tibialis Anterior muscle of the thalidomide group, the degree of atrophy, the number of apoptotic nuclei and the levels of caspases, were similar to those of the CHF controls. CONCLUSIONS: Thalidomide, at the doses used in this study, which are the same employed for the treatment of tubercolosis, leprosy, AIDS and cancer in humans, did not lower either TNFalpha or SPH and only marginally influenced the apoptosis-induced muscle atrophy. Since other TNFalpha blockers are under investigation for improving the clinical status of patients with CHF, the present data could be relevant in the design of randomised clinical trials in humans.