The distribution of blood flow and glucose uptake within single skeletal muscles in the awake rabbit

Abstract

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.

Regional distributions of blood flow and tissue uptake rates of vitamin B12 and albumin within single rabbit skeletal muscles

“…Absolute blood flow values were as previously reported for awake rabbits, i.e. about twice as high as in anaesthetized rabbits (Iversen & Nicolaysen, 1990).…”

“…We have previously demonstrated a significant impact of pentobarbital anaesthesia on the longterm ( > 30 min) time-dependent fluctuations in blood flow (Iversen & Nicolaysen 1990). Thus, it was important to control whether the measured values for tissue uptake rate were affected by anaesthesia.…”

“…T h e perfusion variability as measured by the deposition of microspheres in resting and stimulated muscle regions each weighing about 0.25 g 311 from anaesthetized rabbits, proved to be independent of specific fibre-t!-pe distributions and of sympathetic vasomotor activity (Iversen & Xicolaysen 1989). Recently, we showed that this regional heterogeneity in blood flouwithin single muscles was equally large in awake rabbits (Iversen & Nicolaysen 1990). T h e degree of activity of neither the motorneurons nor the sympathetic vasomotor nerves had any apparent influence on the distribution of regional blood flow within the muscles in these awake rabbits.…”

“…Four rabbits (3.54.1 kg, mixed breed, Group F, see below) were studied while awake. The surgerq-and post-operative surveillance have previously been outlined by Iversen & Nicolaysen ( 1990).…”