The effect of blood flow restriction along with low-intensity exercise on cardiac structure and function in aging rat: Role of angiogenesis

Aims: Low-intensity aerobic training along with limbs blood flow restriction can improve mass and strength of skeletal muscle, but its effects on aging heart structure and performance is unidentified. We investigated the effects of this model of training on myocardial function, histology and angiogenesis in old male rats. Main methods: Animals randomly were divided into control (Ctl), sham-operated (Sh), limbs blood flow restriction (BFR), sham-operated plus 10 weeks low intensity treadmill exercise (Sh + Ex), and BFR plus exercise (BFR + Ex) groups. Finally, blood pressure, heart physiological and stereological parameters, myocardial oxygen consumption index and expression of vascular endothelial growth factor (VEGF) and its receptors (Flt-1 and kdr) were assessed. Key findings: BFR+Ex group had significantly lower heart rate (P < 0.05 vs. Ctl and Sh groups), rate-pressure product (RPP) and left ventricular end diastolic pressure (P < 0.05 and P < 0.01 vs. untrained groups, respectively). BFR + Ex group also had greater +dp/dt max (P < 0.01) and -dp/dt max (P < 0.05) than untrained groups. A significant increase in volumes of left ventricle and myocytes (P < 0.05, vs. Ctl and Sham), ventricular hypertrophy index and capillaries length density (P < 0.05 vs. untrained groups) were observed in BFR + Ex group. The level of VEGF and Flt-1 proteins and their mRNAs increased in the BFR+Ex group compared to Ctl, Sh and BFR (P < 0.01) and Sh+Ex (P < 0.05) groups. The kdr mRNA and its protein level were significantly higher in the BFR + Ex group. Significance: Findings suggest that BFR plus exercise through improving the angiogenesis, physiological cardiac remodeling and oxygen demand/supply matching can promote cardiac performance in the elderly rats.