[Intracellular calcium mobilization and effects of ATP on ampullate crista hair cells of the guinea pig].
OBJECTIVE
To further understand the intracellular calcium mobilization features of the isolated ampullate crista vestibular hair cells(VHCs) and ATP effects on intracellular free calcium concentration([Ca2+]i) in VHCs of the guinea pig.


METHODS
Vestibular hair cells were isolated from the guinea pig crista ampullaris by enzymatic and mechanical methods. The influence of high K+ solution and ATP on [Ca2+]i was investigated. The [Ca2+]i of VHC was examined using laser scanning confocal microscopy(LSCM) and the Ca2+ sensitive dye Fluo-3.


RESULTS
(1) 75 mmol/L K+ Hank's solution resulted in an increase of [Ca2+]i in both the cytoplasm and the cuticular plate of 5 type I VHCs. In the Ca(2+)-free medium, however, 75 mmol/L K+ solution could not induce [Ca2+]i an increase in observed 5 type I VHCs. (2) In the presence of 1.0 mmol/L or 0.1 mmol/L of ATP, there was a rapid reversible rise of the [Ca2+]i in 18/19 type I VHCs. A small response of ATP-induced [Ca2+]i was found only in 1/10 of type I VHC in Ca(2+)-free medium. There was no significant increase in [Ca2+]i when the same volume of Hank's solution was applied to the chamber containing VHCs.


CONCLUSIONS
The result suggests that high K+ solution led to Ca2+ influx via voltage-dependent calcium channels. Extracellular Ca2+ influx is a major source of the ATP-induced [Ca2+]i increase.
Han
W
W
Department of Otorhinolaryngology, General Hospital of PLA, Beijing 100853.
Zhang
S
S
Jiang
S
S
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D005260:Female; D006168:Guinea Pigs; D018069:Hair Cells, Vestibular / Q000187:drug effects / Q000378:metabolism*; D008297:Male
D000255:Adenosine Triphosphate; D002118:Calcium