Reactive hyperemia in capillaries of red and white skeletal muscle

Reactive hyperemia was examined in individual capillaries of the red anterior (ALD) and white posterior (PLD) latissimus dorsi muscles of the anesthetized chicken following total blood flow occlusion of 3.5-180 s in length. Capillary red cell velocities were measured by the dual-slit photometric technique. The control capillary velocities in the ALD and PLD were 0.56 +/- .03 (SE) and 0.34 +/- .03 mm/s, respectively. With increasing occlusion lengths, the reactive hyperemia peak velocity, hyperemia duration, and excess flow were found to increase progressively in both muscles suggesting a metabolic origin for the response. The ALD showed a greater peak reactive hyperemia flow than the PLD following occlusion lengths of 7-60 s and a greater excess flow following occlusion lengths of 15 s and longer. However, when these data were normalized to control velocities by calculating the peak-to-control velocity ratio and percent flow debt repayment, no significant differences were found between the two muscles. Furthermore, the reactive hyperemia durations were similar in the two muscles at each occlusion length. These data demonstrate that reactive hyperemia is similar in two muscle types which are known to differ considerably in resting metabolism and anaerobic capacity.