Change of B-type Natriuretic Peptide Expression during Exercise Preconditioning Induced Myocardial Protection in Rat

Objective:To view the change of B-type natriuretic peptide (BNP) expression during exercise preconditioning and determine whether BNP participated incardioprotective effect of exercise preconditioning.Methods:SD rats were divided into control group (C) , HE group, EEP group, LEP group, EEP+HE group, and LEP+HE group.After establishing of EP animal model, high-intensity exercise on treadmill for inducing myocardial injury.Then the lever of cTnI 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 BNP in myocardium and plasma were detected by immunohistoChemistry and enzyme inked immunosorbent assay respectively.Results:As compared with the group C, there was no significant difference in the level of cTnI and the degree of myocardial ischemia/hypoxia, but it has a significant increase in group HE.Compared with the group C, the expression of BNP in myocardium was increased significantly in group HE, group EEP and group LEP, but the level of BNP in plasma significantly increase only in group HE and group EEP, group LEP has no significant difference.As compared with group HE, there was a significant decrease in the level of cTnI and the degree of myocardial ischemia/hypoxia in group EEP+HE and group LEP+HE.Compared with group HE, the expression of BNP in myocardium was increased significantly in group EEP+HE and group LEP+HE, but the level of BNP in plasma significantly increase only in group LEP+HE, group EEP+HE has no significant difference.Conclusion:exercise preconditioning can induce myocardium to produce BNP, and BNP participated in cardioprotective effect of exercise preconditioning.