[An animal model for cochlear microcirculatory disorders by photochemically initiated thrombosis]

Making an ideal animal model of cochlear microcirculatory disorders is an important method in studying inner ear microcirculation. After intravenous injection of Rose bengal (30 mg/kg), the lateral wall of the cochlea of guinea pigs was illuminated with green light (wavelength: 550 +/- 20 nm). The Rose bengal photoactivatedly produces oxygen radicals and oxygen singlets, which subsequently damage the endotheliocytes to cause adhesion and aggregation of platelets in the small vessels. After the photo-illumination, cochlea blood flow reduced sharply, and CAP amplitude decreased in 10 min and disappeared completely in about 20-40 min. With prolongation of time, stria vascularis, Corti's organ and spiral ganglion cells showed further disintegration due to ischemia, which resembled the histopathological changes of the cochlea with microcirculatory disorders. Therefore, this animal model may be considered an ideal one for studying the mechanisms of hearing loss that was caused by microcirculatory disorders and also for evaluating the effects of drugs on microcirculation of damaged cochlea.