OCCLUSION OF COCHLEAR MICROVESSELS BY PLUGGED LEUKOCYTES IN THE GUINEA PIG EXPOSED TO INTENSE NOISE / 解放军医学杂志

ABSTRACT

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.