title: Electrical properties and gustatory responses of various taste disk cells of frog fungiform papillae.
abstract: We compared the electrical properties and gustatory response profiles of types Ia cell (mucus cell), Ib cell (wing cell), and II/III cell (receptor cell) in the taste disks of the frog fungiform papillae. The large depolarizing responses of all types of cell induced by 1 M NaCl were accompanied by a large decrease in the membrane resistance and had the same reversal potential of approximately +5 mV. The large depolarizing responses of all cell types for 1 mM acetic acid were accompanied by a small decrease in the membrane resistance. The small depolarizing responses of all cell types for 10 mM quinine-HCl (Q-HCl) were accompanied by an increase in the membrane resistance, but those for 1 M sucrose were accompanied by a decrease in the membrane resistance. The reversal potential of sucrose responses in all cell types were approximately +12 mV. Taken together, depolarizing responses of Ia, Ib, and II/III cells for each taste stimulus are likely to be generated by the same mechanisms. Gustatory depolarizing response profiles indicated that 1) each of Ia, Ib, and II/III cells responded 100% to 1 M NaCl and 1 mM acetic acid with depolarizing responses, 2) approximately 50% of each cell type responded to 10 mM Q-HCl with depolarizations, and 3) each approximately 40% of Ia and Ib cells and approximately 90% of II/III cells responded to 1 M sucrose with depolarizations. These results suggest that the receptor molecules for NaCl, acid, and Q-HCl stimuli are equivalently distributed on all cell types, but the receptor molecules for sugar stimuli are richer on II/III cells than on Ia and Ib cells. Type III cells having afferent synapses may play a main role in gustatory transduction and transmission.
authors.affiliation: Division of Integrative Sensory Physiology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki 852-8588, Japan. toshi@net.nagasaki-u.ac.jp
authors.forename: Toshihide
authors.initials: T
authors.lastname: Sato
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Nishishita
authors.forename: Yukio
authors.initials: Y
authors.lastname: Okada
authors.forename: Kazuo
authors.initials: K
authors.lastname: Toda
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D008564:Membrane Potentials / Q000502:physiology*; D008839:Microelectrodes; D011892:Rana catesbeiana; D013649:Taste / Q000502:physiology*; D013650:Taste Buds / Q000166:cytology / Q000502:physiology; D014059:Tongue / Q000166:cytology / Q000502:physiology*