ABSTRACT
<p><b>OBJECTIVE</b>To study muscle atrophy F-box (MAFbx) and muscle ring finger 1 (MuRF1) mRNA expression and its relationship with muscular contraction following free muscle transfer.</p><p><b>METHODS</b>The gracilis muscle was orthotopic transferred in adult rat to establish the animal model. The muscle at the unoperated side was used as control. The expression of MAFbx and MuRF1 mRNA, the muscle contraction and muscle function were measured by real-time PCR and multiple function physiological device. The relationship among the expression of MAFbx and MuRF1 mRNA, the muscle contraction and muscle function was analyzed.</p><p><b>RESULTS</b>After muscle free transfer, muscle wet weight reservation, the maximum contraction and tetanus strength reduce first and increased later, but still lower than those at control side. The expression of MAFbx and MuRF1 mRNA reached peak level 3 - 4 weeks after muscle transfer which was 7.1 and 4.1 times as that at control side. It decreased later, but still higher than that at control side, showing a significant difference between them (P< 0. 05).</p><p><b>CONCLUSIONS</b>Persistent over-expression of MAFbx and MuRF1 mRNA after muscle transfer has a close relationship with muscle atrophy and muscle dysfunction. MAFbx and MuRF1 can be used as markers for early muscle atrophy, and also as potential target for drug treatment of muscle atrophy.</p>
Subject(s)
Animals , Female , Rats , Muscle Contraction , Muscle Proteins , Genetics , Muscle, Skeletal , Pathology , Muscular Atrophy , Genetics , Metabolism , Pathology , RING Finger Domains , RNA, Messenger , Genetics , Rats, Sprague-Dawley , SKP Cullin F-Box Protein Ligases , Genetics , Tripartite Motif Proteins , Ubiquitin-Protein Ligases , GeneticsABSTRACT
Salusin-alpha and salusin-beta are newly identified bioactive peptides with hemodynamic and mitogenic activities. Recent studies have shown that salusins improve calcium uptake and protein synthesis in neonatal rat cardiomyocytes, suggesting that salusins may be regulatory factors for myocardial growth and hypertrophy. In this study, we investigated whether salusins improve the survival of cardiomyocytes after serum deprivation. Cultured neonatal cardiomyocytes were treated with or without salusins (salusin-alpha or salusin-beta) at a concentration range of 10 to 10 mol/L for 24 h under serum deprivation conditions. Cardiomyocytes viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazonium bromide assay. Cell death or apoptosis rate was identified by flow cytometry analysis. Compared to serum deprivation-only groups, cardiomyocyte viability was significantly increased in salusin-alpha or salusin-beta groups. Cell death rate was decreased after administration of 10 mol/L salusin-alpha or salusin-beta. Salusin-beta was able to decrease the apoptotic rate. Salusins also increased the expression of cardiomyocyte glucose-regulated protein 78 (GRP78) as estimated by Western blot. Furthermore, antisense oligodeoxynucleotide specifically against GRP78 attenuated or abrogated antiapoptosis or survival effects of salusin-beta. These findings suggest that salusin-alpha and salusin-beta may be a potential survival factor against serum deprivation-induced myocardial cell death and that this cardioprotective effect may involve an upregulation of GRP78 expression in cardiomyocytes.
Subject(s)
Adenosine Triphosphatases/pharmacology , Apoptosis , Cytoprotection , Heat-Shock Proteins/physiology , Molecular Chaperones/physiology , Myocytes, Cardiac/drug effects , Animals , Animals, Newborn , Cells, Cultured , Culture Media, Serum-Free , Endoplasmic Reticulum Chaperone BiP , Heat-Shock Proteins/analysis , Intercellular Signaling Peptides and Proteins , Molecular Chaperones/analysis , Myocytes, Cardiac/cytology , Oligonucleotides, Antisense/pharmacology , Rats , Rats, Sprague-Dawley , Up-RegulationABSTRACT
<p><b>AIM</b>To investigate the effect of endogenous endothelin-1 (ET-1) on cardiomyocyte apoptosis induced by hypoxia and its possible mechanism.</p><p><b>METHODS</b>Cultured neonatal rat cardiomyocytes were divided into control group and ET receptor antagonist group. Control group was given DMEM only and ET receptor antagonist group was treated with ET receptor subtype A (ET(A)) receptor antagonist BQ610 and BQ123 or ET(B) receptor antagonist BQ788 and subjected to hypoxia for 24 h. The presence of apoptosis in cardiomyocytes was evaluated by TUNEL analysis and flow cytometry (FCM).</p><p><b>RESULTS</b>TUNEL analysis showed that the percentage of positive apoptotic cells in BQ610 5 micromol/L group was 13.2% +/- 3.7%, significantly lower than that in hypoxia group (24.2% +/- 2.2%, P < 0.01). FCM showed that BQ123 (0.04, 0.2 and 1.0 micromol/L) inhibited hypoxia-induced cardiomyocyte apoptosis and increased cardiomyocyte survival rate in a dose-dependent manner, while BQ788 did not show such effects.</p><p><b>CONCLUSION</b>These findings suggest that endogenous ET-1 aggravates hypoxia-induced cardiomyocyte apoptosis and this effect is mediated through ET(A) receptor-dependent pathways.</p>
Subject(s)
Animals , Rats , Animals, Newborn , Apoptosis , Cell Hypoxia , Cells, Cultured , Endothelin A Receptor Antagonists , Endothelin B Receptor Antagonists , Endothelin-1 , Physiology , Myocytes, Cardiac , Metabolism , Pathology , Rats, Sprague-DawleyABSTRACT
Endothelin can affect the contractile properties of cardiacmyocyte, stimulate myocyte growth and myofibrillogenesis, and increase resistance to apoptosis by intracellular signaling pathways. This article briefly reviews the regulative effects of these signaling pathways including protein kinase C, mitogen activated protein kinase, and phosphoinositide 3'-OH kinase/protein kinase B.
