前庭暗細胞におけるカルシウムチャンネルの存在

抄録

To determine whether the functional Ca²⁺ channel exist in the vestibular dark cells, an increase in intracellular Ca²⁺ concentration ([Ca²⁺]i) due to high K⁺ application was measured in dark cells isolated from the ampullae of the semicircular canal of the guinea pig using the Ca²⁺ sensitive dye, Fura-2, and digital imaging microscopy. When 40 mM K⁺was added to the bath, there was a rapid increase in [Ca²⁺]i which returned to the original level after washing. Application of the Ca²⁺ channel blocker, nifedipine (1 μM) blocked the incraese in [Ca²⁺]i. These results suggest the existence of voltage-dependent Ca²⁺ channels in the dark cells, which are presumably involved in the regulation of Ca²⁺ concentration in vestibular endolymph.