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

Murias JM, Grise KN, Jiang M, Kowalchuk H, Melling CWJ, Noble EG. Acute endurance exercise induces changes in vasorelaxation responses that are vessel-specific. Am J Physiol Regul Integr Comp Physiol 304: R574-R580, 2013. First published December 12, 2012; doi:10.1152/ajpregu.00508.2012.-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 mono-exponential function. The overall tau (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 (tau, 18.9 +/- 4.4 s; time-to-steady-state, 80.4 +/- 18.4 s) compared with the aorta (tau, 10.3 +/- 3.8 s; time-to-steady-state, 46.3 +/- 15.2 s), the iliac (tau, 6.3 +/- 2.1 s; time-to-steady-state, 30.3 +/- 9.0 s), and the femoral (tau, 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.