Prolonged treadmill walking attenuates ischemic pressor response and baroreflex control in Yucatan pigs with femoral artery occlusion

Abstract

Exercise‐induced hypertension can be extensive in intermittent claudicants (Bakke et al., 2007), likely due to exaggerated sympathetic activation, in part, from peripheral muscle afferents. To study whether exercise training alleviates this ischemic pressor response, Yucatan pigs (35 to 40 kg) received femoral artery occlusion. One wk later, pigs either ran on a treadmill (12 wk, 5 d/wk, at 3.1 mi/hr 0% grade) until fatigue (~30–60 min) (Tr: n=9), or limited to cage activity (Sed: n=8). A stress test by running @1 to 5 mile/h; Aortic blood pressure (BP), heart rate (HR) and collateral blood flow (BF) were monitored at each speed. Baroreflex function was assessed by adenosine (Aden) or Phenylephrine (PE) i.v. BP was 158±2.8 and 140±3.3 at wk 3, and 135±5.8 and 122±4.1 mmHg at 12 wks in Sed and Tr groups (p<0.05), respectively. BFs was ~24% higher in Tr as compared to Sed animals (122±25.3 ml/min; p>0.05). The slope for HR increase to Aden‐induced BP decline was 0.30±0.11 in Tr and 1.6±0.43 in Sed group (p<0.01); whereas, HR decreases to BP increases by PE were not different between groups. Our data showed that exercise training can reduce the exercise‐pressor response, coincident with a modified baroreflex control and possibly related to a modified peripheral muscle afferent input. These findings imply that physical training can temper the exercise‐triggered hypertension in claudicants.Supported by NIH P01HL 52490