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Objective To observe the effect of tetraethylplyrazine(TMP) on outward K~+ channel of outer hair cells in guinea pig cochlea.Methods 60 guinea pigs were divided into 6 groups randomly in the experiment.Auditory brainstem response was used to monitor the change of ABR thresholds and patch clamp techniques to observe the effect of TMP on outward K~+ channel.Results TMP decreased the elevated ABR threshold caused by streptomycin. The TMP increased the amplitudes of calcium sensitive potassium channels (I_ K(Ca) ) and delayed outward potassium channels (IK) of outer hair cells of guinea pig cochlea.Conclusion The study indicates that TMP may act as a protective agent against ototoxicity of streptomycin. The amplitudes of I_ K(Ca) and IK of outer hair cells are increased by the TMP,suggesting the possible mechanisms of reducing ototoxicity.
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AIM: To study the changes of K + channels of outer hair cells in guinea pig cochlea with streptomycin ototoxicity. METHODS: Auditory brainstem responses (ABR) and whole-cell patch clamp techniques were used.RESULTS: (1) The body weight of guinea pigs with streptomycin ototoxicity decreased significantly; (2) The ABR threshold markedly increased in streptomycin group (Ⅱ,Ⅲ);(3)The number of dissociated outer hair cells of guinea pigs (Ⅱ,Ⅲ) was lower than that of control (Ⅰ); (4) Streptomycin decreased the Ca 2+ -sensitive K + currents and delayed outward K + currents distinctly; (5) There was no significant difference of K + currents between Ⅰ and Ⅱ/Ⅲ. CONCLUSION: These results suggest that the inhibition of K + channels is the basis of streptomycin ototoxicity, but not the direct reason for cell death.
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AIM To analyze the mechanism of the adriamycin induced cardiomyopathy. METHODS The patch clamp technique in the whole cell recording was used to study the effect of adriamycin on L type calcium channel current( I Ca L ) in the isolated cardiomyocyte of the guinea pig. RESULTS The current voltage( I U ) curveshowed the bell shape in the control and in 0 1 mmol?L -1 adriamycin. Their peak potentials were about +10 mV. The amlitude of peak calcium current increased from (-0 93?0 05) nA to (-1 31?0 08) nA( P