Physical Training Reverses the Impaired Cardiac Autonomic Control and Exercise Tolerance Induced by Right-Side Vagal Denervation

Abstract

Cardiac transplantation results in inevitable denervation. However, it remains poorly understood how important the loss of vagal innervation is for exercise tolerance. It is also unclear whether physical working capacity restoration after denervation is assured during exercise. To assess the effect of denervation on cardiac autonomic control and exercise tolerance, we used an animal model of cardiac denervation by unilateral transection of the vagus nerve. The experimental study was carried out on male Wistar rats (N = 60), which were randomly assigned to six groups. One third of animals constituted the control group, the other third underwent right-side vagal denervation, and the rest underwent left-side denervation. After the surgery, half of the animals were trained and the other half were kept sedentary. Electrocardiogram was recorded in all animals, followed by assessment of the heart rate variability. It was shown that the rightside denervation leads to significant decrease in the heart rate variability. The postsurgical maintenance of rats with the right-side denervation in sedentary conditions led to significant decreased exercise tolerance. An increase in the physical working capacity was found in all trained animals but the most significant increase was again observed in rats with the right-side denervation. Moreover, in all trained animals indices of the heart rate variability were significantly higher. These observations allow us to conclude that right-side vagal denervation leads to both a decrease in the cardiac autonomic control and a suppression of physical working capacity. Postsurgical training with submaximal intensity promotes both restoration of the exercise tolerance in all animals and increase in the regulatory neurogenic influences on the sinus node, including rats undergoing vagal denervation.