Taurine modulates calcium influx through L-type voltage-gated calcium channels in isolated cochlear outer hair cells in guinea pigs.
Taurine has been proposed to play a role in calcium modulation. To explore the effect of taurine on intracellular calcium homeostasis of isolated cochlear outer hair cells and on the gentamycin-induced inhibition of calcium influx evoked by high K(+) depolarization, we employed fluo-3 imaging of intracellular calcium ([Ca(2+)](i)) via confocal laser scanning microscopy to measure real-time changes of [Ca(2+)](i). We found that the sole application of taurine (5, 10, 20 mM) induced a transient [Ca(2+)](i) increase in a concentration-dependent manner, which was inhibited either by the application of an L-type calcium-channel blocker nifedipine or a calcium-free medium. Pre-incubation with 1mM gentamicin induced inhibition of [C(a)(2+)](i) elevation evoked by high K(+). Short-term (10 min) exposure with a high level of taurine (20 mM) prevented this inhibition. These results indicated that taurine at a high concentration was able to promote calcium influx through L-type calcium channels in isolated outer hair cells and antagonize gentamycin-induced inhibition of calcium elevation evoked by high K(+) by its calcium homeostatic effect.
Liu
Hai-ying
HY
Laboratory of Hearing, Department of Physiology, The Second Military Medical University, 800 Xiang Yin Road, Shanghai 200433, PR China.
Gao
Wen-yuan
WY
Wen
Wen
W
Zhang
Yan-min
YM
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000502:physiology*; D005839:Gentamicins / Q000494:pharmacology; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000378:metabolism*; D066298:In Vitro Techniques; D042541:Intracellular Space / Q000378:metabolism; D018613:Microscopy, Confocal; D009543:Nifedipine / Q000494:pharmacology; D013654:Taurine / Q000494:pharmacology / Q000502:physiology*
D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D005839:Gentamicins; D013654:Taurine; D009543:Nifedipine; D002118:Calcium