Electrophysiological studies of salt-sensitive taste receptors

Experimental data indicate that the Na ion taste receptor is a Na selective membrane ion channel. This channel appears to have passive properties (it is not voltage-gated). Sodium ions stimulate receptor cells by entering them directly down a favorable electrochemical potential gradient and thereby depolarizing the cells. This presumably leads to the release of neurotransmitter, thereby causing excitation of the taste nerves. This process may require the intervention of voltage-gated Na channels that may depolarize the cells sufficiently to activate Ca channels necessary for Ca entry into the cells prior to the release of neurotransmitter. Anions may either augment or impede the movement of Na, depending on their paracellular permeabilities. The electrical potential across the taste buds, controlled in part by anion permeability across the tight junctions, may be one of the regulatory factors in the release of neurotransmitter