L-精氨酸对肾性高血压大鼠畸变产物耳声发射的影响

目的：观察L-精氨酸（L—Arg）对。肾性高血压大鼠畸变产物耳声发射（DPOAE）的影响。方法：将二肾一夹（2K1C）型肾血管型高血压模型的大鼠24只分成模型对照组和L-Arg治疗组各12只；另设正常对照组12只。动物处死前检测DPOAE，并测定耳蜗组织超氧化物歧化酶（SOD）、丙二醛（MDA）和血浆内皮素（ET）的含量。结果：①与正常对照组比较，模型对照组SBP和血浆ET含量明显升高（分别P〈0．01和P〈0．05）；耳蜗组织MDA平均含量明显升高（P〈0．01）；SOD活力明显下降（P〈0．05）。在70dBSPL的高刺激强度下，3组各频率的DPOAE检出率均为100％；在低刺激强度（49dBSPL）下，模型对照组检出率明显降低，与正常对照组比较在各频率DPOAE检出率差异有统计学意义（P〈0．05或P〈0．01）。模型对照组在各频率DPOAE幅值均有所下降，与正常对照组比较差异有统计学意义（P〈0．05或P〈0．01）。②L—Arg治疗组与模型对照组比较，SBP和血浆ET含量均明显降低（均P〈0．01）；SOD活力明显高于模型对照组（P〈0．05）；耳蜗组织MDA平均含量明显低于模型对照组（P〈0．01）。在低刺激强度（49dBSPL）下，L—Arg治疗组在各频率DPOAE检出率与模型对照组比较差异有统计学意义（P〈0．05或P〈0．01）；DPOAE幅值在各频率与模型对照组比较均有所提高（P〈0．05或P〈0．01），而DPOAE潜伏期差异无统计学意义（P〉0．05）。③L-Arg治疗组与正常对照组相比，上述各指标均无统计学意义（均P〉0．05）。结论：①L—Arg可能通过改变大鼠内耳微循环而影响肾性高血压大鼠DPOAE；②L—Arg可以影响耳蜗组织自由基的代谢，并有利于氧自由基的清除，L-Arg对耳蜗组织氧自由基的清除并不改变其对DPOAE的影响。

The effects of L-Arg on distortion product otoacoustic emission in rats with renovascular hypertension

OBJECTIVE: To study the effects of L-Arg on the distortion product otoacoustic emission(DPOAE) in rats with renovascular hypertension. METHOD: Twenty-four healthy rats were divided into two groups (2K1C group and L-Arg group) and another 12 rats were added as control group. The animals were determined by DPOAE before experiment and then sacrificed. The ET in plasma was measured by radioimmunoassay. The MDA and SOD in cochlear tissues were measured by colorimetric method. RESULT: SBP, ET and MDA of 2K1C group was markedly increased than those of control (P < 0.01, P < 0.05, P < 0.01) while SOD of 2K1C group was noticeably decreased than that of the control group (P < 0.05 ). The incidence rates of DPOAE in high level(70 decibel sound pressure level, dBSPL) stimulus were the same in all three groups at all frequencies. The incidence rates and amplitudes of DPOAE of 2K1C group were noticeably low compared with those of the control group in low level (49 dBSPL) stimulus (P < 0.05 or P < 0.01). SBP, ET and MDA of L-Arg group was remarkably decreased than those of 2K1C group (P < 0.05, P < 0.01, P < 0.05) while SOD of 2K1C group was noticeably increased than that of the control group (P < 0.01). The incidence rates and amplitudes of DPOAE of L-Arg group were noticeably higher than those of the 2K1C group in low level (49 dBSPL) stimulus (P < 0.05, P < 0.01). The latencies of DPOAE were not affected in whole frequencies in three groups. CONCLUSION: (1) L-Arg probably have effect on the DPOAE in rats with renovascular hypertension by changing cochlear microcirculation. (2) L-Arg can affect the metabolism of oxygen free radical in rats with renovascular hypertension and be beneficial to get rid of it, which doesn't change the effects of L-Arg on the DPOAE.