THE DISTRIBUTION OF BLOOD-FLOW AND GLUCOSE-UPTAKE WITHIN SINGLE SKELETAL-MUSCLES IN THE AWAKE RABBIT

We have previously described a substantial regional heterogeneity both in blood flow and in glucose uptake within single skeletal muscles in anaesthetized rabbits. These heterogeneities could be related to effects of anaesthesia. The main goal of the present study was therefore to study regional muscle blood flow and muscle glucose uptake in awake rabbits. We used the microsphere method and the deoxyglucose technique for assessment of regional blood flow and regional glucose uptake respectively. The measurements were performed in 0.25-g regions from hind leg muscles. Some rabbits were first studied while awake and then during anaesthesia. Others were studied while either awake or anaesthetized. The degree of regional heterogeneity in blood flow and in glucose uptake was similar in awake and anaesthetized rabbits. Both temporal and spatial heterogeneity in blood flow were present. Evidence was found for vasomotion with a cycle time exceeding 45 min in awake rabbits. This perfusion pattern was similar in rabbits in which either the motor or sympathetic vasomotor nerves or both had been blocked. We conclude that regional perfusion and glucose uptake within single muscles are also markedly heterogeneous in awake rabbits. Regional, non-synchronized fluctuations in blood flow with a long cycle time seem to be an important part of this perfusion heterogeneity.