Na+-H+ exchange activity in taste receptor cells.
Na+-H+ exchange activity in taste receptor cells.
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味觉感受器细胞中的Na-H交换活性。
DOI：
10.1152/jn.00809.2003
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发表时间：
2004
影响因子：
2.5
通讯作者：
Lyall,Vijay
中科院分区：
文献类型：
--
作者：
Vinnikova,AnnaK;Alam,RammyI;Malik,ShahbazA;Ereso,GlennL;Feldman,GeorgeM;McCarty,JohnM;Knepper,MarkA;Heck,GerardL;DeSimone,JohnA;Lyall,Vijay
用RT-PCR方法检测了菌状和环状味觉感受器细胞（TRCs）中Na+-H+交换器亚型1和3（NHE-1和NHE-3）的mRNA表达。抗NHE-1抗体结合定位于基底外侧膜，抗NHE-3抗体定位于真菌状和轮廓状TRCs的顶膜。在TRC的一个子集中，在细胞内隔室中也检测到NHE-3免疫反应性。对于功能研究，将含有单个菌状乳头的分离舌上皮安装在分离的顶侧和基底侧，并用标称无CO2/HCO 3的生理介质（pH 7.4）灌注。使用荧光比率成像监测TRC的细胞内pH（pHi）和Na+（[Na+]i）的变化。在恒定的外部pH下，1）去除基底外侧Na+可逆性降低pH和[Na+]i;2）HOE 642（一种特异性阻断剂）和阿米洛利（一种基底外侧NHE-1的非特异性阻断剂）减弱pH和[Na+]i的降低;3）TRC暴露于基底外侧NH 4Cl或乙酸钠脉冲诱导pH一过性降低，并自发恢复至基线; 4）pHi恢复被基底外侧阿米洛利抑制，5-（N-甲基-N-异丁基）-阿米洛利（MIA），5-（N-乙基-N-异丙基）-阿米洛利（EIPA）、HOE 642和Na+去除; 5）HOE 642、MIA、EIPA和阿米洛利抑制pH恢复，Ki值分别为0.23、0.46、0.84和29 μM;和6）顶端或基底侧pH降低酸化TRC pH并抑制自发pH恢复。结果表明TRC的基底外侧膜中存在功能性NHE-1。我们假设NHE-1参与酸味转导，因为它的活性在酸刺激过程中受到调节。
mRNA for two Na+-H+-exchanger isoforms 1 and 3 (NHE-1 and NHE-3) was detected by RT-PCR in fungiform and circumvallate taste receptor cells (TRCs). Anti-NHE-1 antibody binding was localized to the basolateral membranes, and the anti-NHE-3 antibody was localized in the apical membranes of fungiform and circumvallate TRCs. In a subset of TRCs, NHE-3 immunoreactivity was also detected in the intracellular compartment. For functional studies, an isolated lingual epithelium containing a single fungiform papilla was mounted with apical and basolateral sides isolated and perfused with nominally CO2/HCO3--free physiological media (pH 7.4). The TRCs were monitored for changes in intracellular pH (pHi) and Na+([Na+]i) using fluorescence ratio imaging. At constant external pH,1) removal of basolateral Na+reversibly decreased pHiand [Na+]i;2) HOE642, a specific blocker, and amiloride, a nonspecific blocker of basolateral NHE-1, attenuated the decrease in pHiand [Na+]i;3) exposure of TRCs to basolateral NH4Cl or sodium acetate pulses induced transient decreases in pHithat recovered spontaneously to baseline;4) pHirecovery was inhibited by basolateral amiloride, 5-(N-methyl-N-isobutyl)-amiloride (MIA), 5-(N-ethyl-N-isopropyl)-amiloride (EIPA), HOE642, and by Na+removal;5) HOE642, MIA, EIPA, and amiloride inhibited pHirecovery withKivalues of 0.23, 0.46, 0.84, and 29 μM, respectively; and6) a decrease in apical or basolateral pH acidified TRC pHiand inhibited spontaneous pHirecovery. The results indicate the presence of a functional NHE-1 in the basolateral membranes of TRCs. We hypothesize that NHE-1 is involved in sour taste transduction since its activity is modulated during acid stimulation.