Asai Y, Umemura K, Nakashima M
Department of Pharmacology, Hamamatsu University School of Medicine, Japan.
Ann Otol Rhinol Laryngol. 1996 Jun;105(6):472-5. doi: 10.1177/000348949610500610.
We investigated the reversibility of compound action potential (CAP) changes induced after transitory local ischemia induced by rose bengal photochemically induced thrombosis of the rat anterior inferior cerebellar artery (AICA). Cochlear blood flow (CBF) was measured with a laser-Doppler flowmeter positioned on the lateral bony wall of the basal turn of the cochlea, and the CAP to an 8-kHz half-wave of sinusoid sound at 100 dB sound pressure level was monitored. The irradiation was started 5 minutes before the rose bengal administration and continued through the thrombosis formation. Tissue-type plasminogen activator (t-PA, 1 mg/kg) dissolved in saline was injected intravenously 2 minutes after complete photothrombotic blockade of the AICA in the rats presenting complete abolition of CAPs just after the vascular occlusions. Nineteen of the 51 rats presented complete abolition of the CAP just after the AICA occlusion, and the thrombosed AICA was successfully reperfused by t-PA administration in 11 of the 19 rats. The result showed that duration of ischemia was the more important determinant for the reversibility of CAPs during the acute phase (p = .00001), and the residual level of cochlear blood flow during ischemia was also an important factor (p = .066). It appeared that the critical time of ischemia for the complete recovery of CAPs was around 5 minutes, and that the critical limit for the irreversibility of CAPs within the acute phase was between 20 and 25 minutes.
我们研究了玫瑰红光化学诱导大鼠小脑前下动脉（AICA）血栓形成所导致的短暂局部缺血后复合动作电位（CAP）变化的可逆性。使用激光多普勒血流仪测量位于耳蜗基底转外侧骨壁上的耳蜗血流量（CBF），并监测在100分贝声压水平下对8千赫正弦波声音的CAP。在给予玫瑰红前5分钟开始照射，并持续至血栓形成。在血管闭塞后立即出现CAP完全消失的大鼠中，在AICA完全光血栓形成阻断后2分钟，静脉注射溶解于生理盐水中的组织型纤溶酶原激活剂（t-PA，1毫克/千克）。51只大鼠中有19只在AICA闭塞后立即出现CAP完全消失，在这19只大鼠中，有11只通过给予t-PA成功实现了血栓形成的AICA再灌注。结果表明，在急性期，缺血持续时间是CAP可逆性的更重要决定因素（p = .00001），缺血期间耳蜗血流量的残余水平也是一个重要因素（p = .066）。似乎CAP完全恢复的缺血临界时间约为5分钟，急性期内CAP不可逆的临界限度在20至25分钟之间。
