强噪声引起的豚鼠耳蜗基底膜微血管白细胞嵌顿及对血流的影响

OCCLUSION OF COCHLEAR MICROVESSELS BY PLUGGED LEUKOCYTES IN THE GUINEA PIG EXPOSED TO INTENSE NOISE

了解噪声暴露后耳蜗微血管内白细胞是否参与微循环障碍的形成。用 16只豚鼠暴露 115dB(SPL)的 4kHz窄带噪声 4h ,2天或 4天后处死。耳蜗行 :①台盼蓝染色 ,标记血管内失活的白细胞 ;②Hoechst33342荧光染色标记毛细胞核。部分动物处死前行静脉注射FITC 右旋糖酐 ,标记血浆 ,处死后观察血管充盈状态。结果 :耳蜗基底膜微血管发现失活的白细胞 ,嵌顿于血管内或分布于血管周围 ,造成红细胞聚集 ,管径增宽。FITC 右旋糖酐标记的血浆未出现在白细胞嵌顿的血管内 ,表明血流被阻断。白细胞嵌顿与毛细胞损伤虽都主要出现在耳蜗一回和二回 ,但二者并不一定发生在同一解剖部位。有趣的是白细胞嵌顿只出现在基底膜微血管 ,而在血管纹微血管内无此病变。提示噪声后白细胞参与耳蜗微循环障碍的形成 ,它对噪声引起的损伤和修复过程的其它影响值得进一步的研究。

Objective To investigate the possible role of leukocytes, a important cellular component of the blood, in the induction of microcirculatory disturbances in noise-exposed cochleae. Methods Guinea pigs were exposed to a 4 kHz narrow band noise at 115 dB SPL for 4 hours, and the exposed cochleae were collected at 2 or 4 days after the noise exposure. Several techniques (cell viability assay, fluorescent labeling for blood plasma and for hair cell nuclei) were used to examine morphological changes in microvessels in the spiral lamina and in the stria vascularis as well as the hair cell nuclei. Results In noise-exposed cochleae, aggregatad leukocytes were found in the vessels of the spiral lamina. In the up-stream of the vessels with aggregated leukocytes, red blood cells were tightly packed, causing an increase in vessel diameters. Most leukocytes were located within the lumen of vessels, but some of them infiltrated the spiral lamina, usually alongside the vessels. Cell viability, assessed by trypan blue staining, showed that these plugged leukocytes lost their viability. In contrast, no leukocytes aggregated in the vessels of the stria vascularis, nor did leukocytes lose their viability. Conclusion In the cochleae exposed to intense noise, leukocytes were trapped in the vessels of the spiral lamina, leading to disturbance of blood flow. The involvement of leukocytes in local damaging processes and the fate of leukocytes need further studies.