Cadiou Hervé, Molle Gérard
UMR 6522 CNRS, IFRMP 23, Université de Rouen, 76821 Mont-Saint-Aignan, France.
Eur Biophys J. 2003 May;32(2):106-12. doi: 10.1007/s00249-002-0271-x. Epub 2003 Jan 23.
Binding of an odorant to its receptor activates the cAMP-dependent pathway, and also leads to inositol 1,4,5-trisphosphate (InsP(3)) production. This induces opening of a plasma membrane channel in olfactory receptor cells (ORCs). We investigated single-channel properties of this channel in the presence of a phospholipase C (PLC) activator (imipramine) and of a potent activator of the InsP(3)/Ca(2+) release channel (adenophostin A) by reconstituting carp olfactory cilia into planar lipid bilayers. In the presence of 53 mM barium as a charge carrier, the addition of 50 microM imipramine induced a current of 1.53+/-0.05 pA at 0 mV. There were two different mean open times (6.0+/-0.6 ms and 49.6+/-6.4 ms). The I/ V curve displayed a slope conductance of 50+/-2 pS. Channel activity was transient and was blocked by neomycin (50 microM). These observations suggest that imipramine may activate the olfactory InsP(3)-gated channel through PLC. Using the same ionic conditions, the application of 0.5 microM adenophostin A triggered a current of 1.47+/-0.04 pA at 0 mV. The I/ V curve displayed a slope conductance of 60+/-2 pS. This channel showed only a single mean open time (15.0+/-0.3 ms) and was strongly inhibited by ruthenium red (30 microM) and heparin (10 microg/mL). These results indicate that adenophostin A and imipramine may act on the ciliary InsP(3)-gated channel and are potentially valuable pharmacological tools for studying olfactory transduction mechanisms.
气味剂与其受体的结合激活了环磷酸腺苷（cAMP）依赖性途径，还导致肌醇1,4,5 - 三磷酸（InsP(3)）的产生。这会诱导嗅觉受体细胞（ORC）中的质膜通道开放。我们通过将鲤鱼嗅觉纤毛重组到平面脂质双分子层中，研究了在磷脂酶C（PLC）激活剂（丙咪嗪）和InsP(3)/Ca(2+)释放通道的强效激活剂（腺嘌呤磷酯A）存在的情况下该通道的单通道特性。在以53 mM钡作为电荷载体的情况下，添加50 microM丙咪嗪在0 mV时诱导出1.53±0.05 pA的电流。存在两种不同的平均开放时间（6.0±0.6毫秒和49.6±6.4毫秒）。电流 - 电压（I/V）曲线显示斜率电导为50±2 pS。通道活性是短暂的，并被新霉素（50 microM）阻断。这些观察结果表明丙咪嗪可能通过PLC激活嗅觉InsP(3)门控通道。在相同的离子条件下，施加0.5 microM腺嘌呤磷酯A在0 mV时触发了1.47±0.04 pA的电流。I/V曲线显示斜率电导为60±2 pS。该通道仅显示单一的平均开放时间（15.0±0.3毫秒），并被钌红（30 microM）和肝素（10 microg/mL）强烈抑制。这些结果表明腺嘌呤磷酯A和丙咪嗪可能作用于纤毛InsP(3)门控通道，并且是研究嗅觉转导机制的潜在有价值的药理学工具。
