Physical Exercise-Induced Cardiovascular and Thermoregulatory Adjustments Are Impaired in Rats Subjected to Cutaneous Artery Denervation

Abstract

This study aimed to investigate the chronic effects of caudal artery denervation on morphometric parameters of the tail vascular smooth muscle and on physical exercise-induced thermoregulatory and cardiovascular adjustments in rats. Male Wistar rats were subjected to caudal artery denervation or the sham procedure. Approximately 26–28 days after these procedures, their thermoregulatory and cardiovascular parameters were evaluated at rest and during or following a fatiguing treadmill run. At the end of the experiments, the rats were euthanized, and samples of their tails were removed to evaluate morphometric parameters of the vascular smooth muscle surrounding the caudal artery. Denervated rats showed morphological adaptations, including increased arterial wall thickness and wall-to-lumen ratios. In resting rats and following the fatiguing exercise, caudal artery denervation barely affected the thermoregulatory and cardiovascular parameters evaluated. By contrast, caudal artery denervation attenuated the increase in tail skin temperature, decreased the spontaneous baroreflex sensitivity, and exacerbated the increases in mean arterial pressure in exercising rats. The increased wall-to-lumen ratio of denervated rats correlated negatively with the maximum tail skin temperature attained or cutaneous heat loss sensitivity but correlated positively with the maximum diastolic blood pressure attained during exercise. In conclusion, cutaneous denervation induces vascular remodeling characterized by morphological adaptations of the tail vascular smooth muscle. This vascular remodeling likely underlies the impaired tail heat loss and blood pressure adjustments in denervated rats subjected to physical exercise. Therefore, we have highlighted the importance of cutaneous vascular innervation integrity in thermal and cardiovascular control in stress-challenged rats. In this sense, our findings advance the understanding of thermoregulatory and cardiovascular system reactions after a sustained cutaneous vascular innervation injury, which is essential for the treatment of some diseases, such as Parkinson's disease and type 1 and type 2 diabetes mellitus.

Rats with higher intrinsic exercise capacities exhibit greater preoptic dopamine levels and greater mechanical and thermoregulatory efficiencies while running

“…A recent study highlighted that tail skin vasodilation does not fully explain heat loss in a running rat; Malheiros-Lima et al (29) reported that rats subjected to tail artery denervation presented greatly impaired tail heat loss, but a normal exercise induced increase in T ABD . In the present study, differences in alternative pathways for dissipating heat other than the tail-skin vasodilation could explain the distinct thermoregulatory efficiencies between the three groups.…”

Comparative effects of two heat acclimation protocols consisting of high-intensity interval training in the heat on aerobic performance and thermoregulatory responses in exercising rats

“…A recent study highlighted that tail-skin vasodilation does not fully explain heat loss in running rats [39]. In this study, the rats subjected to tail artery denervation presented greatly impaired tail heat loss, but a "normal" exercise-induced increase in core temperature.…”

Independent effects of rapid eye movement sleep deprivation and exposure to environmental heat stress on aerobic performance and thermoregulatory responses in exercising rats

“…Because tail vasodilation is the main pathway by which rats dissipate body heat while running [44,62,63], alternative and maybe "underestimated" pathways for dissipating heat (e.g., evaporative breathing) may help explain the lower exercise-induced increase in T CORE in sleepdeprived rats. Interestingly, a recent study failed to report changes in T CORE during exercise, despite an apparent attenuation in the T SKIN increase induced by caudal artery denervation [43].…”

“…In the experiments performed under temperate conditions, T AMB was controlled at 24°C with airconditioning. This T AMB was selected as a temperate environment because previous data suggest that T AMB ranging from 24 to 26°C corresponds to the lower extremity of the thermoneutral zone of resting rats maintained inside the chamber that contained the treadmill belt [37,43,44]. In the warm experiments, the T AMB was controlled at 31°C by using two heaters turned on at 1,200 W (Britânia model AB 1100, Curitiba, Brazil), one positioned in the front and the other in the back of the treadmill, in order to avoid the surging of a temperature gradient in the chamber.…”