Differential transduction mechanisms underlying NaCl- and KCl-induced responses in mouse taste cells.
The transduction mechanism of salt-induced responses of mouse taste cells was investigated using the patch clamp and the local stimulation techniques under quasi-natural conditions. Apically applied NaCl induced a voltage-independent current, which was partially suppressed by amiloride and Cd2+. In contrast, apically applied 0.5 M KCl induced an inwardly rectifying current (KCl-induced Iir). The KCl-induced Iir was unaffected by amiloride. The Iir was suppressed not only by external Ba2+ and Cs+, but also by a Cl- channel blocker, niflumic acid. The Er of the KCl-induced response was independent of the apical ionic concentration, but rather was close to the equilibrium potential of Cl- (E(Cl)) at the basolateral membrane. The KCl-induced Iir displayed a fast run-down under the conditions of the conventional whole cell clamp method, but not under the perforated patch conditions. Immunohistochemical localization of an inwardly rectifying Cl- channel protein, ClC-2, was observed in taste bud cells of the fungiform papillae. It is concluded that the transduction mechanism of NaCl-induced responses is completely different from that of KCl-induced responses in mouse taste cells.
Miyamoto
T
T
Department of Physiology and. Department of Histology, Nagasaki University School of Dentistry, Nagasaki 852-8588, Japan. miyamoto@net.nagasaki-u.ac.jp
Miyazaki
T
T
Fujiyama
R
R
Okada
Y
Y
Sato
T
T
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D000090007:CLC-2 Chloride Channels; D002104:Cadmium / Q000494:pharmacology; D018118:Chloride Channels / Q000378:metabolism; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009544:Niflumic Acid / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D011189:Potassium Chloride / Q000494:pharmacology*; D015398:Signal Transduction; D012965:Sodium Chloride / Q000494:pharmacology*; D013650:Taste Buds / Q000166:cytology / Q000187:drug effects* / Q000502:physiology
D000090007:CLC-2 Chloride Channels; D018118:Chloride Channels; D002104:Cadmium; D012965:Sodium Chloride; D009544:Niflumic Acid; D011189:Potassium Chloride; D000584:Amiloride