Acute endurance exercise induces changes in vasorelaxation responses that are vessel-specific.

The dynamic adjustment and amplitude of the endothelium-dependent vasorelaxation of the carotid, aorta, iliac, and femoral vessels were measured in response to acute low- (LI) or high-intensity (HI) endurance exercise. Vasorelaxation to 10(-4) M ACh was evaluated in 10 control, 10 LI, and 10 HI rats. Two-millimeter sections of carotid, aorta, iliac, and femoral arteries were mounted onto a myography system. Vasorelaxation responses were modeled as a monoexponential function. The overall τ (control, 10.5 ± 6.0 s; LI, 10.4 ± 5.7 s; HI, 11.0 ± 6.9 s) and time-to-steady-state (control, 47.6 ± 24.0 s; LI, 46.2 ± 22.8 s; HI, 49.1 ± 28.3 s) was similar in LI, HI, and control (P > 0.05). The overall (average of four vessel-type) % vasorelaxation was larger in LI (73 ± 16%) and HI (73 ± 16%) than in control (66 ± 19%) (P < 0.05). The overall rate of vasorelaxation was greater in LI (1.9 ± 0.9%·s(-1)) and HI (1.9 ± 1.1%·s(-1)) compared with control (1.6 ± 0.7%·s(-1)) (P < 0.05). The vessel-specific responses (average response for the three conditions) showed that carotid displayed a slower adjustment (τ, 18.9 ± 4.4 s; time-to-steady-state, 80.4 ± 18.4 s) compared with the aorta (τ, 10.3 ± 3.8 s; time-to-steady-state, 46.3 ± 15.2 s), the iliac (τ, 6.3 ± 2.1 s; time-to-steady-state, 30.3 ± 9.0 s), and the femoral (τ, 6.0 ± 1.9 s; time-to-steady-state, 29.3 ± 8.4 s). The % vasorelaxation was larger in the carotid (82 ± 14%) than in the aorta (67 ± 16%), iliac (61 ± 13%), and femoral (71 ± 19%) (P > 0.05). The rate of vasorelaxation was carotid (1.1 ± 0.2%·s(-1)), aorta (1.5 ± 0.4%·s(-1)), iliac (2.2 ± 0.8%·s(-1)), and femoral (2.6 ± 1.0%·s(-1)). In conclusion, an acute bout of endurance exercise increased vascular responsiveness. The dynamic and percent adjustments were vessel-specific with vessel function likely determining the response.