血管内皮舒张因子对豚鼠耳蜗功能的影响

Effects of blood circulation on cochlear microcirculation in the cochlea of guinea pigs

目的探讨血管内皮性一氧化氮合酶(endothelial nitric oxide synthase,eNOS)对耳蜗电位的影响。方法健康豚鼠100只,随机等分为10组:①人工外淋巴液组;②L-精氨酸组;③Ca2+-ATP酶抑制剂组;④Ca2+-ATP酶抑制剂+L-精氨酸组;⑤Ca2+-ATP酶抑制剂+环磷酸鸟苷(cyclic guanosine momophosphate,cGMP)组;⑥Ca2+-ATP酶抑制剂+L-精氨酸+非选择性一氧化氮合酶抑制剂组;⑦神经元性一氧化氮合酶(neurenitric oxide synthase,nNOS)抑制剂组;⑧Ca2+-ATP酶抑制剂+nNOS抑制剂组;⑨Ca2+-ATP酶抑制剂+nNOS抑制剂+L-精氨酸组;⑩Ca2+-ATP酶抑制剂+nNOS抑制剂+L-精氨酸+eNOS抑制剂组。全耳蜗灌流以上各组药物120 min,由蜗窗龛每隔30 min测1次耳蜗微音器电位(cochlear microphonic,CM)和耳蜗听神经复合动作电位(compound action potential,CAP)。结果第3组灌流Ca2+-ATP酶抑制剂前后CAP阈移为28.5 dB SPL,第4组在此基础上加入L-精氨酸可使CAP阈移改善9 dB SPL,与加入cGMP后作用相似。第8组多加入nNOS抑制剂抑制螺旋器的功能后CAP阈移为43 dB SPL,再加入L-精氨酸可使CAP阈移改善7 dB SPL,而第10组加入eNOS抑制剂后CAP阈移较第9组增加6 dB SPL,与第8组无明显差异。免疫组织化学结果显示:L-精氨酸能改善Ca2+-ATP酶抑制剂对eNOS在耳蜗血管纹上表达的影响。结论 NO/cGMP通路可以通过调节血管纹上小动脉的收缩舒张状态,起到调节耳蜗微循环的作用。

OBJECTIVE To study the cochlear microcirculation effects of endothelial nitric oxide synthase（eNOS）of guinea pigs.METHODS Total 100 guinea pigs were divided into 10 groups as follows： ①artificial perilymph;②Ca2＋-ATPase inhibitor;③ L-arginine;④Ca2＋-ATPase inhibitor＋L-arginine;⑤Ca2＋ATPase inhibitor＋cGMP;⑥Ca2＋-ATPase inhibitor＋Larginine＋Non-selective NOS inhibitor;⑦nNOS inhibitor;⑧nNOS inhibitor＋Ca2＋-ATPase inhibitor;⑨ nNOS inhibitor＋Ca2＋-ATPase inhibitor＋L-arginine;⑩ nNOS inhibitor＋Ca2＋-ATPase inhibitor＋L-arginine＋eNOS inhibitor.Perilymphs of guinea pig were perfused with the drugs mentioned above at a rate of 2.5 μl/min for 2 hours.The compound action potential（CAP）was evoked by click,and the cochlea microphnics（CM）evoked by tone burst（1 kHz,rise and fall 2 ms,and plateau 20 ms）.The CAP and CM were recorded from the round window（RM） every 30 minutes.RESULTS The average threshold shift of CAP after perfusing Ca2＋-ATPase inhibitor was 28.5 dB SPL,and its improvement by L-arginine in group 4 was 9 dB SPL,similar to group 5.The threshold shift of CAP in group 8 was 43 dB SPL,and additional improvement of 7 dB SPL showed out after L-arginine added.Compared with group 9,more 6 dB SPL of improvement was got in group 10 after eNOS inhibitor added which has no obvious differences with group 8.Immunohistochemical results showed that L-arginine can improve the eNOS expression on cochlear striae vascularis.CONCLUSION ENOS can regulate cochlear microcirculation by adjusting contract and dilation of small artery on cochlear striae vascularis.