Voltage-gated Ca2+ channels in type III taste cells

In the mammalian taste bud, the heterogeneous cell population includes three morphologically distinct types of cells, type I to type III, which are also different in their electrophysiological features. Particularly, voltage-gated (VG) Ca2+ channels are functional solely in taste cells of the type III. These channels were studied here with external Ba2+ ions as current carriers. It was specifically shown that VG Ba2+ currents were almost completely blockable with nifedipine as well as with ionic blockers, such as Cd2+, Ni2+, and Co2+. Kinetic properties of VG Ba2+ currents in type III cells and their sensitivity to the blockers indicated that these currents were largely mediated by VG Ca2+ channels of the L-type. The expression of genes, which encode pore-forming α1-subunits of Ca2+ channels, was analyzed using methods of molecular biology. Among four genes encoding L-type Ca2+ channel α1-subunits (Cav 1.1-Cav1.4), the expression of Cav1.2 was demonstrated in taste cells. © Pleiades Publishing, Ltd. 2009.