Alterations Of Atrial Natriuretic Peptide Expression During Exercise Preconditioning-induced Cardioprotection In Rat

Objective:exercise preconditioning( EP) in cardioprotection plays an important role in protecting effect, and its mechanism has been clarified and revealed. Atrial natriuretic peptide(ANP) to determine the heart is not only a blood pump, also have endocrine function. ANP in sodium diuresis, diastolic blood vessels and plays a very important role in functional of myocardial oxygen. Accordingly, the experiment on the basis of our previous studies, EP on right atrial tissue expression of ANP and the influence of changes in the EP early and late cardioprotection to effect right atrium tissue ANP and possible mechanism. In order to further enrich EP myocardial cardioprotection mechanism of research methods and update the theoretical and experimental basis for development of training programs.Methods: 150 adult male Sprague-Dawley rats, the rats weight stratified sampling, and were randomly assigned into 6 groups as a Group for comparison group(C); high-intensity exercise(HE); early exercise preconditioning group(EEP); late exercise preconditioning group(LEP); early exercise preconditioning plus high exercise group(EEP+HE); late exercise preconditioning plus high exercise group(LEP+HE). The present research literature and other scholars, the subjected to a high-intensity interval exercise protocol, as EP model. Useing a high-intensity treadmill exercise leads to exercise-induced myocardial injury. Then the lever of c Tn I was detected by chemiluminescent immunoassay. HE staining was used to observe the changes in ventricular structure. Hematoxylin-basic fuchsin-picric acid(HBFP) staining and Chromotrope 2R-Brilliant green(C-2R) staining were evaluated the degree of myocardial ischemia/hypoxia. The change of ANP in plasma was detected by enzyme inked immunosorbent assay. The change of ANP in myocardium was detected by immunohisto Chemistry and Western blot. Expression of ANP m RNA in right atrium tissue of rats was detected by Real-time PCR assay.Results: 1. Myocardial injury evaluation indexes and the degree of protection: Compared with group C, HE plasma c Tn I levels significantly increased, of myocardial tissue C-2R and HBFP dyeing MOD value significantly increased, with significant difference(P< 0.05); Compared with group C, EEP and LEP plasma c Tn I levels, the myocardial tissue of C-2R and HBFP dyeing MOD value has no obvious change, does not have significant difference(P > 0.05); Compared with HE group, EEP + HE group and LEP+HE plasma c Tn I levels significantly decreased and myocardial tissue C-2R and HBFP dyeing MOD value significantly reduced, with significant difference(P < 0.05); Compared with EEP+HE group, plasma c Tn I levels LEP+HE group was obviously higher, myocardial tissue C-2R and HBFP dyeing MOD value significantly increased, with significant difference(P< 0.05). 2. Plasma ANP level changes: Compared with group C, HE plasma ANP level group, the EEP group has no obvious change; Compared with group C, the LEP group of plasma ANP level have obvious rise, but the difference is not significant(P> 0.05); Compared with HE group, EEP+HE group and LEP+HE plasma ANP levels significantly increased, with significant difference(P< 0.05); Compared with EEP+HE group, LEP+HE set of plasma ANP level significantly increased, with significant difference(P < 0.05). 3. Right atrium tissue ANP immunohistochemical results: Compared with group C, HE group, EEP and LEP group right atrium tissue ANP immune response MOD value significantly increased, with significant difference(P< 0.05); Compared with HE group, EEP+HE group and LEP+HE right atrium tissue ANP immune response MOD value significantly increased, with significant difference(P< 0.05). Than to the EEP+HE group, LEP+HE set right atrium tissue ANP immune response MOD values have obvious rise phenomenon, but the difference is not significant(P> 0.05). 4. Western blot analysis of ANP in right atrium tissue: Compared with group C, HE and LEP group right atrium tissue ANP level significantly increased, with significant difference(P< 0.05); Compared with group C, group EEP right atrium tissue ANP level have obvious rise, but the difference is not significant(P> 0.05); Compared with HE group, EEP+HE set right atrium tissue ANP level significantly increased, with significant difference(P< 0.05); Compared with the group HE, LEP+HE set right atrium tissue ANP level has obvious drop phenomenon, but the difference is not significant(P> 0.05). 5. ANP m RNA in situ hybridization of right atrium tissue: Compared with group C, HE group, EEP and LEP right atrium tissue ANP m RNA in situ hybridization positive signal MOD value increased significantly, with significant difference(P< 0.05); Compared with HE group, EEP+HE group and LEP+HE right atrium tissue ANP m RNA in situ hybridization positive signal MOD value significantly increased, with significant difference(P<0.05); Than to the EEP+HE group, LEP+HE set right atrium tissue ANP m RNA in situ hybridization positive signal MOD value significantly increased, with significant difference(P< 0.05). 6. Right atrium myocardial tissue ANP m RNA real-time fluorescent quantitative PCR: Compared with group C, HE group, EEP right atrium tissue ANP m RNA level has significantly increased, with significant difference(P> 0.05); Compared with group C, the LEP group right atrial tissue ANP m RNA level have obvious rise, but the difference is not significant(P> 0.05); Compared with HE group, EEP+HE group and LEP+HE right atrium tissue ANP m RNA level significantly increased, with significant difference(P < 0.05); Compared with EEP+HE group, LEP+HE set right atrium tissue ANP m RNA level significantly increased, with significant difference(P< 0.05).Conclusion: EP can attenuate high-intensity exercise-induced myocardial injury in the early and the late phases of cardioprotection, especially during the early phase of EP. EP by raising right atrium tissue ANP m RNA level, promote right atrium tissue expression of ANP increases, cause the increase of plasma ANP level. In the EP in the early and late protective effect, plasma ANP and right atrium tissue ANP were involved in the EP on exercise-induced myocardial damage of cardioprotection.