Nagura M, Iwasaki S, Wu R, Mizuta K, Umemura K, Hoshino T
Department of Otolaryngology, Hamamatsu University School of Medicine, Japan.
Eur J Pharmacol. 1999 Jan 29;366(1):47-53. doi: 10.1016/s0014-2999(98)00881-4.
We evaluated the ability of various drugs to prevent the decrease in focal cochlear blood flow induced by photochemical reaction and investigated the mechanisms underlying this decrease. By means of a photochemical reaction, which produces reactive oxygen species, focal lesions measuring about 1 mm in diameter were induced in the lateral wall of the guinea pig cochlea. The protective effects of hydrocortisone, amidotrizoate and ATP on cochlear blood flow and cochlear vascular conductance changes were evaluated by using a non-contact laser flowmeter. Cochlear blood flow and cochlear vascular conductance were decreased to 65.1+/-4.9% (mean +/- S.E.M.) and 57.0+/-3.7% (mean +/- S.E.M.) of the initial level 30 min after the start of the photochemical reaction, respectively. Hydrocortisone significantly prevented the decline in the cochlear blood flow and cochlear vascular conductance and reduced the area of stria vascularis degeneration in a dose-dependent manner. Neither amidotrizoate nor ATP significantly prevented the decrease in cochlear blood flow or cochlear vascular conductance. Hydrocortisone was more effective than vasodilators or other agents which increase cochlear blood flow in preventing the photochemically induced decrease in cochlear blood flow. This might be due to the antioxidative effects of hydrocortisone.
我们评估了多种药物预防光化学反应诱导的耳蜗局部血流减少的能力，并研究了这种减少背后的机制。通过光化学反应产生活性氧，在豚鼠耳蜗外侧壁诱导出直径约1毫米的局灶性病变。使用非接触式激光流量计评估氢化可的松、泛影葡胺和三磷酸腺苷对耳蜗血流和耳蜗血管传导变化的保护作用。光化学反应开始30分钟后，耳蜗血流和耳蜗血管传导分别降至初始水平的65.1±4.9%（平均值±标准误）和57.0±3.7%（平均值±标准误）。氢化可的松显著预防了耳蜗血流和耳蜗血管传导的下降，并以剂量依赖的方式减少了血管纹变性的面积。泛影葡胺和三磷酸腺苷均未显著预防耳蜗血流或耳蜗血管传导的减少。在预防光化学诱导的耳蜗血流减少方面，氢化可的松比血管扩张剂或其他增加耳蜗血流的药物更有效。这可能归因于氢化可的松的抗氧化作用。
