Cochlear microcirculation in young and old gerbils.
Human postmortem studies as well as epidemiologic investigations have implicated the peripheral vascular system as one of the etiologic factors of presbycusis. This study uses the surface dissection microsphere method for regional cochlear blood flow analysis and morphometric techniques for quantifying capillary density in the stria vascularis. In this study 11 old and 10 young gerbils were used. Our results indicate that blood flow in the cochlea was decreased in the old gerbils. This decrease was most obvious in the lateral portion (stria vascularis). The decrease of blood flow in older animals was clearly not related to loss of strial capillaries with aging. The decreased flow to the lateral portion must arise from either decreased perfusion pressure or from increased vascular resistance. This decreased blood flow in the aged animals supports a vascular theory of presbycusis.