Effect of exercise training on cutaneous microcirculation in rats.

Aim. Exercise training is known to improve endothelium-dependent relaxation in the coronary and skeletal muscle arteries. However, the effects of exercise training on peripheral nonworking tissue, including microcirculation, are still unclear. Therefore, we investigated the effect of chronic and regular aerobic exercise on cutaneous microvascular endothelial function in rats. Methods. We assessed the effect of physical training on skin microcirculation in 7 sedentary (SED) and 21 training rats (Wistar-Kyoto), submitted to a treadmill training protocol (15 m/min; 15% incline; 60 min/day; 8 weeks). Training rats were divided into 3 groups, exercising 1 day/week (Ex1), 3 days/week (Ex3) or 5 days/week (Ex5). Cutaneous blood flow was recorded before the beginning of the training protocol, after 4 weeks and at the end of the training program. Hyperemic response (RH) was the flow reaction obtained after sudden release of the garrot. For data analysis, cutaneous vascular conductance (CVC) was indexed as cutaneous blood flow divided by mean arterial blood pressure (in millimeters of mercury, mmHg) and normalized to baseline values. Results. At baseline, CVC was not different among groups (SED or training) at 3 steps of experimental protocol. The hyperemic stimulus significantly increased normalized CVC only in group Ex3 after 4 weeks (P<0.006) and 8 weeks (P<0.006). Conclusion. Exercise training exerts a generalized effect on the vasculature by increasing endothelial function in vessel beds different from those perfusing actively working muscle. However, some differences exist since training at a frequency of 3 bouts weekly only modifies cutaneous microcirculation.