Amiloride-sensitive NaCl taste responses are associated with genetic variation of ENaC α-subunit in mice

Noriatsu Shigemura, Tadahiro Ohkuri, Chiharu Sadamitsu, Keiko Nakano, Ryusuke Yoshida, Gary K. Beauchamp, Alexander A. Bachmanov, Yuzo Ninomiya

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Abstract

An epithelial Na+ channel (ENaC) is expressed in taste cells and may be involved in the salt taste transduction. ENaC activity is blocked by amiloride, which in several mammalian species also inhibits taste responses to NaCl. In mice, lingual application of amiloride inhibits NaCl responses in the chorda tympani (CT) gustatory nerve much stronger in the C57BL/6 (B6) strain than in the 129P3/J (129) strain. We examined whether this strain difference is related to gene sequence variation or mRNA expression of three ENaC subunits (α, β, γ). Real-time RT-PCR and in situ hybridization detected no significant strain differences in expression of all three ENaC subunits in fungiform papillae. Sequences of the β- and γENaC subunit genes were also similar in the B6 and 129 strains, but αENaC gene had three single nucleotide polymorphisms (SNPs). One of these SNPs resulted in a substitution of arginine in the B6 strain to tryptophan in the 129 strain (R616W) in the αENaC protein. To examine association of this SNP with amiloride sensitivity of CT responses to NaCl, we produced F2 hybrids between B6 and 129 strains. Amiloride inhibited CT responses to NaCl in F2 hybrids with B6/129 and B6/B6 αENaC R616W genotypes stronger than in F2 hybrids with 129/129 genotype. This suggests that the R616W variation in the αENaC subunit affects amiloride sensitivity of the ENaC channel and provides evidence that ENaC is involved in amiloride-sensitive salt taste responses in mice.

Original languageEnglish
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume294
Issue number1
DOIs
Publication statusPublished - Jan 1 2008

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Epithelial Sodium Channels
Amiloride
Single Nucleotide Polymorphism
Salts
Chorda Tympani Nerve
Genotype
Genes
Tongue
Tryptophan
In Situ Hybridization
Arginine
Real-Time Polymerase Chain Reaction

All Science Journal Classification (ASJC) codes

  • Physiology

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Amiloride-sensitive NaCl taste responses are associated with genetic variation of ENaC α-subunit in mice. / Shigemura, Noriatsu; Ohkuri, Tadahiro; Sadamitsu, Chiharu; Nakano, Keiko; Yoshida, Ryusuke; Beauchamp, Gary K.; Bachmanov, Alexander A.; Ninomiya, Yuzo.

In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 294, No. 1, 01.01.2008.

Research output: Contribution to journalArticle

Shigemura, Noriatsu ; Ohkuri, Tadahiro ; Sadamitsu, Chiharu ; Nakano, Keiko ; Yoshida, Ryusuke ; Beauchamp, Gary K. ; Bachmanov, Alexander A. ; Ninomiya, Yuzo. / Amiloride-sensitive NaCl taste responses are associated with genetic variation of ENaC α-subunit in mice. In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology. 2008 ; Vol. 294, No. 1.
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