The use of coloured dye‐extraction microspheres to measure blood flow in rabbit skeletal muscle: a validation study with special emphasis on repeated measurements

Abstract

SUMMARYWe evaluated the use of coloured dye-extraction microspheres for measuring blood flow in the skeletal muscle of anaesthetized rabbits. Spheres were injected into the left atrium after sternotomy or lateral thoracotomy, 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 different colour were well correlated. Resting flows were difficult to measure, 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 digitorum longus muscles after injection of a total of 15 x 106 spheres.Injection via the left ventricle, a closed-chest procedure, gave a more stable preparation than injections via the left atrium. However, in both cases there was a progressive decline in hyperaemic muscle blood flow during a series of injections. These results indicate that it is possible to use this technique to measure skeletail muscle blood flow in the rabbit, but that it is difficult to exploit the advantages of sequential microsphere injection in this species.

Development of the Fluorescent Microsphere Technique for Quantifying Regional Blood Flow in Small Mammals

“…Nevertheless, complete sedimentation was achieved by the use of ethanoic solutions, which presumably increased the specific gravity difference between microspheres and medium, aided by higher centrifugation speeds than used previously (van Oosterhout et al 1995;Hakkinen et al 1995;Tan et al 1997). Interestingly, while the recovery of pure coloured microspheres was similar to that obtained with FMs, in contrast to the present study the presence of tissue appeared to reduce the efficiency of recovery (Degens et al 1996).…”

“…Indeed, on injecting a much greater number of coloured microspheres in rabbits than was used in the present study, when corrected for differences in body weight, Degens et al (1996) found that < 10% of capillaries were blocked in TA and EDL muscles. Although blood flows were higher with FM than RM measurements in some tissues from rats that were separately injected with either radioactive or fluorescent microspheres, these data can be explained by seasonal differences in temperature, as the FM study was performed in summer and RM experiments in winter, and are most unlikely to reflect different microsphere quality.…”

“…A number of non-radioactive alternatives have been proposed, including coloured microspheres (Hale et al 1988;Kowallik et al 1991;Hakkinen et al 1995;Degens et al 1996) and X-ray fluorescent microspheres (Morita et al 1990;Mori et al 1992), although they have been shown to have some disadvantages. For example, coloured microspheres may underestimate RBF, since they have limited resolution due to significant spectral overlap among different colours, while data variance is high as a result of the low signal intensity (Hale et al 1988;Kowallik et al 1991;Prinzen & Glenny, 1994;Degens et al 1996).…”

“…For example, coloured microspheres may underestimate RBF, since they have limited resolution due to significant spectral overlap among different colours, while data variance is high as a result of the low signal intensity (Hale et al 1988;Kowallik et al 1991;Prinzen & Glenny, 1994;Degens et al 1996). The X-ray fluorescent microspheres technique uses a measurement system that is expensive and not in common use (Prinzen & Glenny, 1994).…”

Blood flow of the gluteus medius muscle

“…Normally, resting muscle blood flow is reported to be in a range between 3-8ml/min/100 g. This blood flow is increased up to 10 times when the muscle is contracted, although the blood flow was also influenced by intramuscular pressure [2,6,8]. Although the resting blood flow in this report was higher than that in other reports, our results demonstrate that blood flow in the gluteus medius muscle decreases significantly when it has been dissected (mobilised) two-thirds from its proximal or distal origins.…”