ABSTRACT
This study investigated the impact of lifelong sedentariness on skeletal muscle mass and mitochondrial function. Thirty C57BL/6 strain mice (2 months) were randomly divided into three groups (young-Y; old sedentary-OS; old active-OA). Young animals were sacrificed after 1 week of quarantine, and OS and OA groups were individually placed into standard cages and in cages with running wheels, respectively, until sacrifice (25 months). Body weights and hind-limb skeletal muscle wet weights were obtained from all groups. Mitochondrial respiratory functional measures (i.e., state 3 and 4 respiration, respiratory control ratio, and ratio of nanomoles of ADP phosphorylated by nanomoles of O2 consumed [ADP/O]) and biochemical markers of oxidative damage (aconitase activity, protein carbonyl derivatives, sulfhydryl groups) were measured in isolated mitochondrial suspensions. Our results reveal that lifelong sedentary behavior has a negative impact on the age-related loss of skeletal muscle mass and on the isolated mitochondrial function of mixed skeletal muscle of mice, which is associated with an increased oxidative damage to mitochondrial biomolecules.
Subject(s)
Aging/physiology , Mitochondria, Muscle/physiology , Muscle, Skeletal/physiology , Physical Conditioning, Animal , Aconitate Hydratase/metabolism , Adenosine Diphosphate/pharmacology , Animals , Citrate (si)-Synthase/metabolism , Mice , Mice, Inbred C57BL , Oxidative Stress , Oxygen Consumption , PhosphorylationABSTRACT
A proteomics characterization of mice soleus and gastrocnemius white portion skeletal muscles was performed using nuclear, mitochondrial/membrane, and cytosolic subcellular fractions. The proposed methodology allowed the elimination of the cytoskeleton proteins from the cytosolic fraction and of basic proteins from the nuclear fraction. The subsequent protein separation by two-dimensional gel electrophoresis prior to mass spectrometry analysis allowed the detection of more than 600 spots in each muscle. In the gastrocnemius muscle fractions, it was possible to identify 178 protein spots corresponding to 108 different proteins. In the soleus muscle fractions, 103 different proteins were identified from 253 positive spot identifications. A bulk of cytoskeleton proteins such as actin, myosin light chains, and troponin were identified in the nuclear fraction, whereas mainly metabolic enzymes were detected in the cytosolic fraction. Transcription factors and proteins associated with protein biosynthesis were identified in skeletal muscles for the first time by proteomics. In addition, proteins involved in the mitochondrial redox system, as well as stress proteins, were identified. Results confirm the potential of this methodology to study the differential expressions of contractile proteins and metabolic enzymes, essential for generating functional diversity of muscles and muscle fiber types.
Subject(s)
Muscle, Skeletal/metabolism , Proteomics/methods , Animals , Electrophoresis, Gel, Two-Dimensional , Male , Mice , Muscle Proteins/analysis , Proteome/analysisABSTRACT
The aim of this study was to investigate the influence of ecstasy (MDMA) administration on body temperature and soleus muscle histology in exercised and non-exercised mice. Charles-River mice were distributed into four groups: Control (C), exercise (EX), MDMA treated (M), and M + EX. The treated animals received an i.p. injection (10 mg/kg) of MDMA (saline for C and EX), and the exercise consisted of a 90 min level run at a velocity of 900 m/h, immediately after the MDMA or saline administration. Body temperature was recorded every 30 min via subcutaneous implanted transponder. Animals were sacrificed 1.5, 25.5, and 49.5 h after i.p. injection and the soleus muscles were removed and processed for light and electron microscopy. The MDMA-treated animals showed a significant increase in body temperature (similar in M and M + EX groups), reaching the peak 90 min after i.p. administration; their temperature remained higher than control for more than 5 h. The EX group evidenced a similar and parallel, yet lower temperature increase during exercise and recovery. Morphological signs of damage were rarely encountered in the EX group; they were more pronounced in M group and even aggravated in M + EX group. In conclusion, MDMA and exercise per se increased body temperature but in conjunction did not have a cumulated effect. However, ecstasy and concomitant physical activity might severely accumulate with regard to skeletal muscle toxicity and may lead to rhabdomyolysis.
Subject(s)
Hallucinogens/toxicity , Motor Activity/physiology , Muscle, Skeletal/drug effects , N-Methyl-3,4-methylenedioxyamphetamine/toxicity , Animals , Body Temperature/drug effects , Fever/chemically induced , Fever/pathology , Male , Mice , Microscopy, Electron, Transmission , Muscle, Skeletal/pathology , Random Allocation , Rhabdomyolysis/chemically inducedABSTRACT
BACKGROUND: The purpose of this study was to verify a partial bursa-side rupture of the rotator cuff (RC) using different imaging techniques with special emphasis on the validity of a specific method of subacromial arthrography (SAA). METHODS: Patients (n=92, mean age 53.8 years) with a subacromial impingement syndrome underwent sonography, magnetic resonance imaging (MRI), and SAA. All diagnostic results were checked by subsequent arthroscopic surgery. RESULTS: Of 31 surgically verified ruptures, 17 showed a partial rupture located towards the bursa. These had been detected by MRI and ultrasound with a sensitivity of 64% and 41%, respectively, while SAA as a diagnostic tool yielded a sensitivity of 82%. In 14 cases of complete RC ruptures, all imaging techniques had a similar sensitivity of 86-93%. CONCLUSION: It appears that SAA is an adequate and valid diagnostic tool for the detection of partial bursa-sided RC ruptures. Ultrasound and MRI showed a comparably lower sensitivity. It is therefore concluded that SAA has clear advantages in the diagnosis of this defect with the consequence that open surgical techniques can be avoided.
