THE USE OF COLORED DYE-EXTRACTION MICROSPHERES TO MEASURE BLOOD-FLOW IN RABBIT SKELETAL-MUSCLE - A VALIDATION-STUDY WITH SPECIAL EMPHASIS ON REPEATED MEASUREMENTS

We evaluated the use of coloured dye-extraction microspheres for measu ring blood flow in the skeletal muscle of anaesthetized rabbits. Spher es were injected into the left atrium after sternotomy or lateral thor acotomy, or into the left ventricle via the left carotid artery. Both routes of administration produced adequate mixing of microspheres with the blood. In general, the values of flow obtained from spheres of di fferent colour were well correlated. Resting flows were difficult to m easure, owing to the low number of spheres and the correspondingly low absorption of the samples. Occlusion of the capillary bed by trapped spheres was less than 10% in both tibialis anterior and extensor digit orum longus muscles after injection of a total of 15 x 10(6) spheres. Injection via the left ventricle, a closed-chest procedure, gave a mor e stable preparation than injections via the left atrium. However, in both cases there was a progressive decline in hyper aemic muscle blood flow during a series of injections. These results indicate that it is possible to use this technique to measure skeletal muscle blood flow in the rabbit, but that it is difficult to exploit the advantages of s equential microsphere injection in this species.