The effects of combined pre- and post-myocardial infarction exercise on microvessel density and vascular endothelial growth factor signaling / 中华物理医学与康复杂志

ABSTRACT

Objective:To investigate the effect of exercise both before and after myocardial infarction (MI) on microvessel density in the left ventricle, and on the mRNA and protein expression of vascular endothelial growth factor (VEGF) and its receptors.Methods:Ninety-six male Sprague-Dawley rats were randomly divided into a sedentary sham operation group (Sed-Sh), a pre-MI exercise sham operation group (PreE-Sh), a sedentary MI group (Sed-MI), a pre-MI exercise group (PreE-MI), a post-MI exercise group (PostE-MI) and a combined exercise group (ComE-MI). The rats of the exercise groups underwent 60min of treadmill training daily five times a week for five weeks, while those of the Sed-Sh and Sed-MI groups remained sedentary. Then all of the rats underwent either an operation to induce an acute MI (Sed-MI, PreE-MI, PostE-MI and ComE-MI groups) or a sham MI operation (Sed-Sh and PreE-Sh groups). Four weeks after the operation, the exercise groups underwent five days adaptive training, followed by 8 weeks of 60min of treadmill training daily, five times a week. All of the rats were then sacrificed. The microvessel densities in the infarcted and uninfarcted volumes were detected using Factor VIII-related antigen staining, while the mRNA expressions of VEGF and its receptors were examined using a real-time polymerase chain reaction. The protein expressions of VEGF and its receptors were measured using western blotting.Results:Compared with Sed-MI group, the average microvessel densities of the PostE-MI and ComE-MI groups had increased significantly, with the average density of the PostE-MI group significantly higher than that of the PreE-MI group, but significantly lower than the ComE-MI group′s average. Compared with the Sed-MI group, the average mRNA expression of VEGF and its receptors in the PostE-MI and ComE-MI groups was significantly higher, without significant differences between the two groups.Conclusions:Pre-MI exercise does not significantly improve left ventricular function or microvessel density, while post-MI exercise does, as it can upregulate the expression of VEGF and its receptors to activate VEGF signaling. The increase in microvessel density may benefit left ventricular remodeling and cardiac function.