Postnatal development of membrane excitability in taste cells of the mouse vallate papilla.
The mammalian peripheral taste system undergoes functional changes during postnatal development. These changes could reflect age-dependent alterations in the membrane properties of taste cells, which use a vast array of ion channels for transduction mechanisms. Yet, scarce information is available on the membrane events in developing taste cells. We have addressed this issue by studying voltage-dependent Na+, K+, and Cl- currents (I(Na), I(K), and I(Cl), respectively) in a subset of taste cells (the so-called "Na/OUT" cells, which are electrically excitable and thought to be sensory) from mouse vallate papilla. Voltage-dependent currents play a key role during taste transduction, especially in the generation of action potentials. Patch-clamp recordings revealed that I(Na), I(K), and I(Cl) were expressed early in postnatal development. However, only I(K) and I(Cl) densities increased significantly in developing Na/OUT cells. Consistent with the rise of I(K) density, we found that action potential waveform changed markedly, with an increased speed of repolarization that was accompanied by an enhanced capability of repetitive firing. In addition to membrane excitability changes in putative sensory cells, we observed a concomitant increase in the occurrence of glia-like taste cells (the so called "leaky" cells) among patched cells. Leaky cells are likely involved in dissipating the increase of extracellular K+ during action potential discharge in chemosensory cells. Thus, developing taste cells of the mouse vallate papilla undergo a significant electrophysiological maturation and diversification. These functional changes may have a profound impact on the transduction capabilities of taste buds during development.
Bigiani
Albertino
A
Dipartimento di Scienze Biomediche, Sezione di Fisiologia, Università di Modena e Reggio Emilia, 41100 Modena, Italy.bigiani@unimo.it
Cristiani
Rosella
R
Fieni
Francesca
F
Ghiaroni
Valeria
V
Bagnoli
Paola
P
Pietra
Pierangelo
P
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000375:Aging / Q000378:metabolism*; D000818:Animals; D002452:Cell Count; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology*; D018118:Chloride Channels / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology; D024642:Potassium Channels, Voltage-Gated / Q000037:antagonists & inhibitors / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D026941:Sodium Channel Blockers; D015222:Sodium Channels / Q000378:metabolism; D013650:Taste Buds / Q000166:cytology / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D015293:Transducin / Q000378:metabolism
D018118:Chloride Channels; D002712:Chlorides; D026902:Potassium Channel Blockers; D024642:Potassium Channels, Voltage-Gated; D026941:Sodium Channel Blockers; D015222:Sodium Channels; C075192:gustducin; D013779:Tetrodotoxin; D012964:Sodium; D015293:Transducin; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D011188:Potassium