抄録
Frog taste discs consist of morphologically and physiologically diverse types of cells. Recently, Suwabe and Kitada have demonstrated the properties of voltage-gated inward currents of type Ib, type II and type III cells in frog taste discs. However, little is known about the properties of outward currents of these cells. To investigate the properties of outward currents of morphologically identified cells, patch clamp technique was used to make recordings from taste cells in vertical slices of taste disc. Cell types were identified by staining with Alexa Fluor 488 hydrazide in a pipette. We recorded voltage-gated potassium outward currents from all recorded type Ib, II and III cells under the sodium-free Ringer perfusion. Peak amplitudes of outward currents of type Ib and III cells were significantly larger than that of type II cells. Outward currents were composed of delayed rectifier current, transient potassium currents and calcium activated potassium currents. Type Ib and II cells exhibited delayed rectifying potassium currents and transient potassium currents. Type III cells exhibited all three types of outward potassium currents. Calcium activated potassium currents of type III cells were sensitive to apamin and charybdotoxin. These observations demonstrate that the properties of potassium currents are different among cell types and suggest that the roles in taste reception and transduction of each cell types may differ. [J Physiol Sci. 2006;56 Suppl:S182]
