Study of perivascular innervation in arteries from post-myocardial infarction rats: effect of physical training

Abstract

Acute myocardial infarction (MI) accounts for 23% of mortality due to cardiovascular diseases in the world. MI survivors usually show symptoms of heart failure (HF), associated with a significant reduction in life expectancy after a heart attack. In addition to changes in heart tissue, the authors observed an increase in peripheral vascular resistance due to activation of neurohumoral system in HF, as well as modifications on the different mechanisms which control vascular tone. Several studies have described the presence of endothelial dysfunction in aorta, caudal and mesenteric artery in rats subjected to permanent occlusion of the coronary artery, which is a MI model. Mesenteric vascular bed is of great importance to the vascular resistance control, since mesenteric blood flow can constitute up to 20-30% of total cardiac output. Thus, the mesenteric vascular bed acts as a blood reservoir, thus contributing to the redistribution of blood from the abdominal area into the systemic circulation, in order to maintain the blood flow to the vital organs. Mesenteric vascular bed tone is modulated by several factors, including endothelial and nervous factors. The perivascular innervation plays a major role in the regulation of vascular tone. Changes in the participation of the different components of the mesenteric perivascular innervation (sympathetic, nitrergic and sensory) may contribute to the alterations in blood flow in different pathophysiological situations. However, although the importance of the research, once the decreased cardiac output activates the renin-angiotensin-aldosterone and sympathetic systems, there are no studies analyzing the possible modification of the various components of the mesenteric perivascular innervation in an experimental model of MI. It has been described that moderate physical exercise normalizes the elevated sympathetic activity observed following MI, and increases endothelial NO release. Additionally, it has been reported that exercise reduces oxidative stress observed in MI, thereby increasing NO bioavailability. Thus, the objective of this project is to evaluate possible changes in mesenteric perivascular innervation function (sympathetic, nitrergic and sensory) in rats after MI, and the possible effect of moderate aerobic training on these changes. (AU)