Muscle blood flow in trained rats with peripheral arterial insufficiency

The influence of exercise training on the recovery of muscle blood flow was assessed in rats with bilateral stenosis of the femoral artery, sufficient to limit exercise hyperemia in the distal hindlimb but not alter resting blood flow. Muscle blood flow was measured with 141Ce-labeled microspheres (15 microns) during treadmill running at 20 m/min in normal (n = 10), acute stenosed (n = 9), sedentary stenosed (n = 10) and trained stenosed (n = 13) animals. Treadmill training by a progressively intense program (up to 1 h/day, 7 days/wk for 6 wk) improved exercise tolerance evident both in duration and intensity of exercise. Total hindlimb blood flow (ml.min-1.100 g-1) was not different (P greater than 0.05) between all stenosed groups but was only 46-63% that of the normal group (P less than 0.05). Acute stenosis reduced distal blood flow to only 22% of that in the proximal hindlimb tissue. A significant (P less than 0.05) but limited recovery of distal limb blood flow (to 44% of proximal) occurred in sedentary stenosed rats after 6 wk of cage activity. Training further increased (P less than 0.05) distal limb blood flow to 69% of proximal. This partial recovery of distal limb blood flow could reflect a greater collateral vessel function or an enhanced vascularity of the distal limb tissue. Our results illustrate that peripheral adaptations occur within the ischemic hindlimb of trained animals to redistribute the limited O2 delivery to the active muscles most affected by stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)