Attenuation of streptomycin ototoxicity by tetramethylpyrazine and its effect on K⁺ channels in the outer hair cells of guinea pig cochlea.

In order to elucidate the mechanism underlying the attenuation of streptomycin ototoxicity by tetramethylpyrazine (TMP), the present study investigated the effect of TMP on the outward K(+) current in the outer hair cells of guinea pig cochlea. Sixty guinea pigs were divided into 6 groups randomly. Auditory brainstem response (ABR) was used to observe the change in thresholds and to evaluate ototoxicity induced by streptomycin. Whole-cell patch-clamp technique was used to observe the effect of TMP on outward K(+) current in isolated outer hair cells. The results showed that TMP attenuated the threshold shift caused by streptomycin and increased the amplitudes of Ca(2+)-sensitive K(+) current [I(K(Ca))] in the outer hair cells. The present data suggest that TMP displays anti-ototoxicity induced by streptomycin. The augmented amplitudes of I(K(Ca)) of the outer hair cells induced by TMP may be one of the mechanisms underlying its ototoxicity-attenuating effect.