The effect of short‐term exercise training on the skeletal muscle vascular response to sympathetic stimulation

Abstract

The effect of 4 weeks of exercise training (ET) on skeletal muscle sympathetic vasoconstriction was investigated. It was hypothesized that vascular responsiveness to sympathetic stimulation would be increased following ET. Sprague-dawley rats were randomly assigned to sedentary (S: n=12), mild- (M: 20m.min−15% grade; n=13) or heavy-intensity (H: 40m.min−15% grade, n=8) ET groups. Rats were trained 5d.week−1 for 4 weeks with total training volume matched between ET groups. Rats were anesthetised and instrumented with indwelling catheters and a femoral artery flow probe. The vascular response to lumbar sympathetic chain stimulation delivered continuously at 2Hz or in patterns at 20 or 40Hz was determined. The change in femoral vascular resistance (FVR) was calculated and expressed in arbitrary resistance units (RU). Basal blood flow (S: 4±1, M: 3±1, H: 4±1 mL·min−1), MAP (S: 100±14, M: 90±14, H: 89±15 mmHg) and FVR (S: 33±15, M: 27±5, H: 25±7 mmHg.mL·min−1) were similar between groups (p>0.05). Lumbar chain stimulations produced a smaller (p<0.05) increase in FVR at all frequencies in S (2Hz: 7±3; 20Hz: 9±4; 40Hz: 11±5 RU) compared to M (2Hz: 14±4; 20Hz: 18±4; 40Hz: 18±6 RU) and H (2Hz: 21±4; 20Hz: 27±6; 40Hz: 28±4 RU). These data demonstrate that following ET, the vascular response to sympathetic stimulation was up-regulated in a manner dependent on the intensity of training stimulus. NSERC Canada.