ABSTRACT
Objective To observe the heart protective effect of exercise preconditioning (EP) in the acute exhaustion exercise (EE) rats, and explore its action mechanism further. Methods Eighty healthy male Sprague-Dawley (SD) rats were divided into control group (C group), EP group, EE group, and EP+EE group randomly, with 20 rats in each group. The rats in EP and EP+EE groups were trained for 3 weeks according to the daily swimming for 60 minutes (swimming 15 minutes, resting 5 minutes, repeating 3 times) with 6 days each week. The rats in EE and EP+EE groups on the last 1 day after 3 weeks, 3% weight heavy weight was carried once for swimming EE. Two hours after the last EE, abdominal aortic blood and heart was harvested, the levels of serum MB isoenzyme of creatine kinase (CK-MB) and calcitonin gene related peptide (CGRP) were determined by enzyme linked immunosorbent assay (ELISA); the ultrastructure of myocardium was observed by optical microscopy; the levels of myocardial malondialdehyde (MDA) and superoxide dismutase (SOD) were determined by ELISA, the mRNA expression of myocardial CGRP was assayed by reverse transcription-polymerase chain reaction (RT-PCR), and the protein expression of myocardial CGRP was assayed by Western Blot. Results Compared with C group, the levels of serum CK-MB and myocardial MDA were significantly increased, serum CGRP content, myocardial SOD activity, and mRNA and protein expressions of myocardial CGRP were significantly decreased in EE group and EP+EE group. Compared with EE group, the levels of serum CK-MB and myocardial MDA in EP+EE group were decreased [CK-MB (U/L): 13.11±0.77 vs. 15.55±0.90, MDA (μmol/L): 389.57±49.60 vs. 709.08±160.49], the level of serum CGRP, and mRNA and protein expressions of myocardium CGRP were increased [serum CGRP (ng/L): 120.41±9.07 vs. 97.97±9.05, CGRP mRNA (2 -ΔΔCT): 0.45±0.09 vs. 0.14±0.02, CGRP protein (gray value): 0.78±0.08 vs. 0.41±0.04, all P < 0.05], the degree of myocardial injury was obviously alleviated. There was no significant difference in the indexes between the EP group and C group. Conclusion EP has the heart protective effect for the acute EE rats, and the mechanism is closely related to the endogenous protective substance CGRP.
ABSTRACT
Objective To investigate the incidence and clinical characteristics and look for assay or examination indexes or indicators with higher sensitivity and specificity of heart damage induced by exhaustive exercise in order to establish its preliminary clinical classification and diagnostic criteria. Methods In a military region for training staff,the clinical data of 88 soldiers who were admitted to the departments of cardiology in 6 general or central hospitals because of exhaustive exercise from January 2000 to December 2010 were analyzed. The myocardial enzyme, electrocardiogram(ECG),echocardiography and other related examination indexes or indicators were observed,and the changes of symptoms,signs and other relevant assay and examination indexes before and after treatment were recorded. Results Exhaustive exercise could cause the symptoms such as chest tightness,palpitations,chest pain, dizziness,shortness of breath,fatigue,syncope and other symptoms,as well as cardiac auscultation abnormalities. After treatment, aspartate aminotransferase〔AST(U/L):20.34±6.33 vs. 35.43±25.25〕,α-hydroxybutyrate dehydrogenase〔α-HBDH(U/L):130.47±9.04 vs. 168.93±62.69〕,lactate dehydrogenase〔LDH(μmol?s-1?L-1):2.48±0.62 vs. 3.58±1.34〕,creatine kinase〔CK(U/L):125.58±67.56 vs. 556.42±381.89〕,creatine kinase isoenzyme〔CK-MB(U/L):11.20±4.08 vs. 23.09±15.61〕were significantly lower than those before treatment(P<0.05 or P<0.01);cardiac troponin T(cTnT)was detected in 5 patients,its level after treatment was significantly lower than that before treatment(μg/L:0.07±0.05 vs. 1.26±0.78,P<0.05). The ECG abnormalities included primarily sinus bradycardia (16 cases),sinus arrhythmia (13 cases) and premature ventricular contractions (11 cases). Echocardiographic abnormalities appeared in 18 cases,they were chiefly as follows:valvular regurgitation, cardiac dysfunction,cardiac enlargement,etc,among which the most common one was valvular regurgitation(all the refluxes were of small amount). Based on the above clinical manifestations and examination results,the exhaustive cardiac injuries were preliminarily divided into common type(20 cases),arrhythmia type(56 cases),heart failure type(2 cases)and sudden death(10 cases). Conclusions The clinical manifestations of exhaustive heart damage may appear in different types. Abnormal changes of myocardial enzymes,ECG and echocardiography are the strong evidences for the damage. Clinicians should pay attention to its prevention and treatment.
ABSTRACT
Objective To investigate the effects of (?)doxazosin [(?)DOX] and its enantiomers on the myocardial morphology,cell cycle and cell apoptosis in rabbits fed with high fat diet. Methods Male New Zealand white rabbits were fed with high fat diet for 4 weeks. Forty such rabbits with hyperlipemia were then divided into atherogenic diet group (model),model + (-)doxazosin [(-)DOX] group,model + (+)doxazosin [(+)DOX] group and model + (?)DOX group (10 each). Another 10 rabbits were included as normal control group. In those drug-treated groups,1.0mg/kg of doxazosin or its enantiomers were intraperitoneally administered for 9 weeks; rabbits in normal control group and atherogenic diet group were given sterile distilled water. Percentages of myocardial cells in G0/G1 phase and in S phase,proliferation index (PI) and apoptotic rate of myocardial cells were compared among the groups,and the effects of doxazosin and its enantiomers were evaluated. Results Of the animals in atherogenic diet group,the proportion of myocardial cells in G0/G1 phase increased significantly (P0.05). No histomorphological alterations were observed in myocardial cells of the rabbits in normal control group. Pathological changes in myocardial cells were observed in the rabbits of atherogenic diet group,such as vacuolar degeneration,fatty degeneration,focal myocardial necrosis,myocardial fibrosis and focal lymphocyte infiltration. The pathological changes in myocardial cells were significantly ameliorated in the animals in (-)DOX and (?)DOX group,but aggravated in the rabbits of (+)DOX group. Conclusions A long term treatment with (-)DOX in the rabbits may improve the histopathological changes in myocardial cells caused by high fat diet. (-)DOX and (+)DOX may have a optical selective effect.