[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.