[Experimental study of sodium nitroprusside on whole cell calcium currents of outer hair cells in the cochlear of guinea pigs].
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 selectively block the L-type calcium channels on outer hair cells (n = 6).


CONCLUSIONS
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.
Zhou
Jian-bo
JB
Department of Otorhinolarygology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
Kong
Wei-jia
WJ
D000818:Animals; D020746:Calcium Channels, L-Type / Q000187:drug effects* / Q000502:physiology; D003051:Cochlea / Q000166:cytology / Q000502:physiology; D004594:Electrophysiology; D005260:Female; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000378:metabolism / Q000502:physiology*; D008297:Male; D009599:Nitroprusside / Q000494:pharmacology*; D018408:Patch-Clamp Techniques
D020746:Calcium Channels, L-Type; D009599:Nitroprusside