Vascular adaptations in rat hindlimb skeletal muscle after voluntary running-wheel exercise.
To test the hypothesis that voluntary running-wheel exercise would elicit vascular adaptations in rat skeletal muscle, male Sprague-Dawley rats (202 +/- 5 g) were cage confined (C, n = 11) or housed in cages with free access to running wheels (R, n = 13) for 12 wk. Vascular transport capacity was determined in maximally vasodilated (papaverine) hindquarters of C and R rats with measurements of total and regional (radiolabeled microspheres) flow capacity and capillary filtration coefficient. R rats voluntarily ran 29 +/- 4 km/wk over the 12-wk period; however, performance of individual rats varied greatly (range 4-74 km/wk). Citrate synthase activity was increased in the medial head (81%, P < 0.001) and the red long head (88%, P < 0.001) of the triceps brachii muscle in R rats but not in the white long head (25%, P = 0.06). Capillary filtration coefficient was 27% greater in R compared with C rats (0.040 +/- 0.003 vs. 0.031 +/- 0.002 ml.min-1.100 g-1.mmHg-1, respectively, P < 0.001) suggesting that there was an increase in microvascular surface area available for fluid exchange. Total hindquarters flow was increased in R rats (P < 0.05) at all perfusion pressures examined, indicative of an increased flow capacity. Regional flows revealed that skin flow was unchanged in R rats and that the increase in total flow was due to increased skeletal muscle flow capacity. These results indicate that voluntary running-wheel exercise elicits adaptive increases in skeletal muscle vascular transport capacity and oxidative capacity comparable to those seen in treadmill-trained rats and support the use of voluntary running-wheel exercise as a less stressful training modality in exercise studies using rats.
Sexton
W L
WL
Department of Physiology, Kirksville College of Osteopathic Medicine, Missouri 63501, USA.
D000222:Adaptation, Physiological; D000818:Animals; D001808:Blood Vessels / Q000502:physiology; D002196:Capillaries; D006614:Hindlimb / Q000098:blood supply*; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D018482:Muscle, Skeletal / Q000098:blood supply*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow; D014836:Volition