颈上神经节切除对豚鼠耳蜗血流及听性脑干反应阈的影响

目的研究豚鼠颈交感神经节对耳蜗血流及听觉生理功能的调节作用。方法在正常豚鼠单侧耳蜗螺旋蜗轴动脉局部滴加逆行追踪剂辣根过氧化物酶(horseradishperoxidase,HRP),观察双侧交感颈上神经节、星状神经节内的阳性神经元分布;建立单侧颈上神经节切除模型,观察术后不同时间点双侧耳蜗血流、听性脑干反应的情况;建立单侧颈上神经节切除后噪声性听损伤模型,观察颈上神经节切除对噪声损伤导致的听觉阈移是否有保护作用。结果耳蜗螺旋蜗轴动脉局部给予逆行追踪剂后同侧颈上神经节内可见阳性神经元;单侧颈上神经节切除1周后,术侧耳蜗底回血管纹处血流较对侧升高,听性脑干反应阈值无明显变化;颈上神经节切除对噪声导致的听损伤有一定的保护作用。结论交感颈上神经节切除对豚鼠耳蜗血流及听觉生理功能有一定的影响。     

Effect of aging on blood flow in rat larynx

OBJECTIVE/HYPOTHESIS: Age-associated muscular changes and fatigue have been shown to affect phonatory function. Reductions in blood flow with aging could translate to reductions in oxidative capacity within laryngeal muscles and increased fatigability. We tested the hypothesis that there would be increased capillary red blood cell (RBC) velocity and a reduction of capillary density in the thyroarytenoid (TA) muscle of senescent rats. STUDY DESIGN/METHODS: Ten male Fisher 344/Brown Norway rats in two age groups were used: young adult (9 mo) and old (28-30 mo). Sixteen additional young and old rats were used in a fluorescent microsphere experiment that examined blood flow rates before and after a surgical manipulation. With use of a specially equipped intravital microscope, in vivo measurements of capillary geometry and flow were obtained, including RBC velocity, capillary density, tortuosity, and number of branch points. RESULTS: There was an age-related reduction in capillary surface area as evidenced by reduced lineal density of capillaries. In addition, reduced RBC transit time was suggested by the reduction in branch points found with age. There was no change in RBC velocity with aging. The surgical method used to expose the TA muscle for blood flow recordings did not significantly affect resultant blood flow measurements. CONCLUSIONS: We developed a method to evaluate in vivo laryngeal microvasculature. We found age-related changes in microvascular geometry within the TA muscle of the rat that could affect blood flow to this critical muscle of phonation and airway protection. These microvascular changes could contribute to age-related laryngeal dysfunction.