BLOOD-FLOW RESPONSE TO TREADMILL RUNNING IN THE RAT SPINOTRAPEZIUS MUSCLE

The rat spinotrapezius muscle has been utilized to investigate the mic rocirculatory consequences of exercise training. It was the purpose of this investigation to determine whether, and to what extent, this mus cle is recruited during treadmill exercise. Radioactive 15-mu m micros pheres were used to measure blood flow to the spinotrapezius and hind limb musculature as well as to the abdominal organs of female Wistar r ats. Blood Bows were measured at rest and during two levels of treadmi ll-running exercise (i.e., 0% grade, 15 m/min and 10% grade, 24 m/min) . As expected, exercise increased blood flow to the solcus, plantaris, red gastrocnemius, mixed gastrocnemius, and white gastrocnemius muscl es, whereas blood flow to the stomach, intestines, pancreas, spleen, a nd kidneys was decreased (P < 0.05). However, contrary to our expectat ion, blood flow to the spinotrapezius muscle decreased from 61 +/- 6 m l . 100 g(-1). min(-1) at rest to 39 +/- 2 ml . 100 g(-1). min(-1) at 0% grade, 15 m/min and 46 +/- 4 ml . 100 g(-1). min(-1) at 10% grade, 24 m/min (P < 0.05). These findings support the premise that treadmill running does not recruit the spinotrapezius muscle and suggest that p revious training-induced arteriolar adaptations produced in this muscl e may result from mechanisms unrelated to augmented exercise blood flo w or muscle metabolism.