Cochlear blood flow in the rat. A comparison of 10- and 15-micron spheres

The microsphere method combined with surface preparation dissection is described for measuring cochlear blood flow in the rat. Two sphere sizes, 10 and 15 micron, were compared. No difference between the two sizes was found for measuring total cochlear blood flow. Shunting of the 10-micron spheres appeared to be similar to shunting of the 15-micron spheres and thus was minimal. However, the 15-micron spheres distributed poorly to the apical cochlea, especially the spiral portion. The 10-micron sphere was less toxic, allowing larger numbers of spheres to be infused. Consequently, more 10-micron spheres lodged in the cochlea, which is important for reducing random error. For these reasons, we recommend the 10-micron sphere, as opposed to the 15-micron sphere, for studying cochlear blood flow in the rat.