硝普钠对豚鼠耳蜗外毛细胞全细胞钙电流作用的实验研究

Experimental study of sodium nitroprusside on whole cell calcium currents of outer hair cells in the cochlear of guinea pigs

目的 探讨一氧化氮供体———硝普钠 (sodiumnitroprusside ,SNP)对豚鼠单离耳蜗外毛细胞钙电流的影响及作用机制。方法 利用急性分离的豚鼠耳蜗外毛细胞 ,在全细胞膜片钳电压钳记录技术下 ,通过分离离子电流成分的方法 ,记录豚鼠耳蜗外毛细胞全细胞钙电流。结果 SNP对内向钙电流有抑制作用 ,在钳制电位为 -60mV ,刺激电压为 + 10mV的条件下 ,10mmol/L的SNP能抑制 (61 12± 1 99) %的内向钙电流 ( x±s ,n =5)。从 5～ 8个细胞得到的量效关系曲线中 ,其半数作用浓度为 1 9mmol/L ,最大抑制浓度为 10 0mmol/L ,斜率为 0 98。作用的机制为SNP可选择性地阻断外毛细胞膜上的L 型钙通道 (n =6)。结论 SNP作为一氧化氮的一种供体 ,能影响豚鼠耳蜗外毛细胞的生理功能 ,是通过阻断外毛细胞L

Objective To study the effects and mechanism of sodium nitroprusside(SNP),a donor of nitric oxide, on the calcium currents of isolated outer hair cells(OHCs) from the cochlear of guinea pigs Methods Acute isolated outer hair cells of guinea pigs were performed, and the whole cell patch clamp recording techniques were used The K +?Na + ions were excepted to study effects of SNP on the calcium currents of outer hair cells Results SNP inhibited the inward calcium currents of OHCs Under the condition of holding at -60 mV and stimulation voltage as +10 mV, SNP (10 mmol/L) inhibited (61 12±1 99)% of the whole cell′s calcium currents (n=5) A dose-reaction response was obtained from 5～8 cells The half inhibiting concentration was 1 9 mmol/L while the maximum inhibiting concentration was 100 mmol/L, but Hill coefficient was 0 98 SNP could select ively block the L-type calcium channels on outer hair cells (n=6) Conclusion As a donor of nitric oxide, SNP could affect the physiology function of outer hair cells by inhibition of the calcium currents by blocking the L-type calcium channels