| Objective: To investigate the effects and mechanisms of moderate intensity continuous exercise (MICT) and high intensity intermittent exercise (HIIT) on cardiac function in mice with chronic kidney disease (CKD). Methods: A total of 24 male C57BL/6J mice aged 6-8 weeks were randomly divided into Sham group (n=6), CKD group (n=6), CKD+MICT group (n=6) and CKD+HIIT group (n=6). Only the renal capsule was removed in Sham group, and 5/6 kidneys were removed in other groups to establish CKD model. Mice in CKD+MICT group and CKD+HIIT group underwent 2 weeks adaptive training and exercise intervention for 8 weeks after surgery. After intervention, the heart morphology and function of mice were observed by ultrasound. Renal function was assessed by blood urea nitrogen (BUN) and serum creatinine (SCr). The pathological injury and fibrosis of kidney and heart tissue were observed. The structure of myocardial mitochondria was observed by electron microscopy. Mito-chondrial DNA（mtDNA）,NADH dehydrogenase subunit 1（ND-1）,peroxisome proliferator-activated receptor γ coactivator 1α（PGC-1α）,mitochondrial transcription factor A（TFAM） and ATP synthase were de-termined by real-time PCR. Finally, the changes of superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in myocardium were detected with kit. Results: Compared with Sham group, body weight, left ventricular ejection fraction (LVEF), the ratio of early to late diastolic peak velocities (E/A value) , myocardial total SOD activity, myocardial mtDNA copy number and mRNA expression levels of myocardial mitochondria-related factors in the other 3 groups were significantly decreased (P<0.001,0.01，0.05). SCr and BUN, glomerular injury score, renal tubule fibrosis index, myocardial fibrosis index, the ratio of E-wave velocity to averaged E’ velocities of the mitral media and lateral annuli (E/E’value) and myocardial MDA content were significantly increased (P<0.001,0.01,0.05). Compared with CKD group, body weight, LVEF，E/A value, myocardial total SOD activity, myocardial mtDNA copy number and expression levels of myocardial mitochondrial indexes in 2 exercise intervention groups were increased (P<0.001,0.01,0.05). SCr and BUN, glomerular injury score, renal and myocardial fibrosis index, E/E’value，myocardial MDA content, and the degree of myocardial mitochondrial swelling and vacuolation were all decreased (P<0.001,0.01,0.05). Compared with CKD+MICT group，myocardial MDA content and E/E’value were decreased (P<0.001，0.01,0.05). LVEF，E/A value, myocardial total SOD activity, myocardial mtDNA copy number and expression levels of myocardial mitochondrial indexes of CKD+HIIT group were significantly increased (P<0.01,0.05).Conclusion: Both HIIT and MICT can improve the cardiac function of CKD mice, and HIIT can improve the cardiac function more significantly, which may be related to the reduction of mitochondrial dysfunction and oxidative stress damage. |
