Proteomic Investigation of Changes in Rat Skeletal Muscle after Exercise-Induced Fatigue

The mechanisms of exercise-induced fatigue have not been investigated using proteomic techniques, an approach that could improve our understanding and generate novel information regarding the effects of exercise. In this study, the proteom alterations of rat skeletal muscle were investigated during exercise-induced fatigue. The proteins were extracted from the skeletal muscle of SD rat thigh, and then analyzed by two-dimensional electrophoresis and PDQuest software. Compared to control samples, 10 significantly altered proteins were found in exercise samples, two of them were upregulated and eight of them were downregulated. These proteins were identified by MALDI TOF-MS. The two upregulated proteins were identified as MLC1 and myosin L2 (DTNB) regulatory light-chain precursors. The eight decreased proteins are Glyceraldehyde-3-phosphate Dehydrogenas (GAPDH); Beta enolase; Creatine kinase M chain (M-CK); ATP-AMP Transphosphorylase (AK1); myosin heavy chain (MHC); actin; Troponin I, fast-skeletal muscle (Troponin I fast-twitch isoform), fsTnI; Troponin T, fast-skeletal muscle isoforms (TnTF). In these proteins, four of the eight decreased proteins are related directly or indirectly to exercise induced fatigue. The other proteins represent diverse sets of proteins including enzymyes related to energy metabolism, skeletal muscle fabric protein and protein with unknown functions. They did not exhibit evident relationship with exercise-induced fatigue. Whereas the two identified increased proteins exhibit evident relationship with fatigue. These findings will help in understanding the mechanisms involved in exercise-induced fatigue.

Expression of cTnT in rabbit hearts during myocardial ischemia and its postmortem stability / 法医学杂志

OBJECTIVE@#To study the postmortem stability of cTnT as well as its expression alteration, and to evaluate it in the diagnosis of early myocardial ischemia in forensic practice.@*METHODS@#Animal model of early myocardial ischemia was established by rabbit coronary artery ligation. The expression of cTnT in myocardium at different postmortem intervals was detected using immunohistochemistry and analyzed using imaging technique and statistics. The results were then compared between the experimental and control groups.@*RESULTS@#In ischemic myocardium, the expression of cTnT showed prominent focal or flaky depletion in myocardial cytoplasm with no expression detected in interstitium. The expression level showed a linear decrease with prolonged postmortem interval, and disappeared completely on day 14 after death while stored at 4 degrees C. However, there were significant differences in the expression levels of cTnT between experimental and control groups from day 1 to day 7 after death.@*CONCLUSION@#Immunohistochemical detection of cTnT for diagnosis of early myocardial ischemia in corpses stored at 4 degrees C must be performed within 7 days after death.

Immunohistochemical study with depletion of cardiac troponin T in rats on early myocardial ischaemia / 法医学杂志

OBJECTIVE@#To study the depletion of cardiac troponin T in Rats of early myocardial ischaemia.@*METHODS@#Immunohistochemical method (LSAB) was used and the depletion area of CTnT in myocardial ischaemia were measured by the computer image analysis.@*RESULTS@#There is obviously depletion of CTnT after 15 min in myocardial ischaemia of rats, the mean of CTnT depletion of myocardial ischaemic group is significant difference compared with that of the control group (P < 0.01), and the depletion area increased with the prolongagtion of ischaemic time.@*CONCLUSION@#The depletion of CTnT is one of sensitive signs of early myocardial ischaemia.