WIN 17317-3, a New High-Affinity Probe for Voltage-Gated Sodium Channels

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• 作者：Siegmund G. Wanner ; Hartmut Glossmann ; Hans-G&uuml ; nther Knaus ; Robert Baker ; William Parsons ; Kathleen M. Rupprecht ; Richard Brochu ; Charles J. Cohen ; William Schmalhofer ; McHardy Smith ; Vivien Warre
• 刊名：Biochemistry
• 出版年：1999
• 出版时间：August 24, 1999
• 年：1999
• 卷：38
• 期：34
• 页码：11137 - 11146
• 全文大小：120K
• 年卷期：v.38,no.34(August 24, 1999)
• ISSN：1520-4995

文摘

The iminodihydroquinoline WIN 17317-3 was previously shown to inhibit selectively thevoltage-gated potassium channels, K_v1.3 and K_v1.4 [Hill, R. J., et al. (1995) Mol. Pharmacol. 48, 98-104; Nguyen, A., et al. (1996) Mol. Pharmacol. 50, 1672-1679]. Since these channels are found inbrain, radiolabeled WIN 17317-3 was synthesized to probe neuronal K_v1 channels. In rat brain synapticmembranes, [³H]WIN 17317-3 binds reversibly and saturably to a single class of high-affinity sites (K_d2.2 ± 0.3 nM; B_max 5.4 ± 0.2 pmol/mg of protein). However, the interaction of [³H]WIN 17317-3 withbrain membranes is not sensitive to any of several well-characterized potassium channel ligands. Rather,binding is modulated by numerous structurally unrelated sodium channel effectors (e.g., channel toxins,local anesthetics, antiarrhythmics, and cardiotonics). The potency and rank order of effectiveness of theseagents in affecting [³H]WIN 17317-3 binding is consistent with their known abilities to modify sodiumchannel activity. Autoradiograms of rat brain sections indicate that the distribution of [³H]WIN 17317-3binding sites is in excellent agreement with that of sodium channels. Furthermore, WIN 17317-3 inhibitssodium currents in CHO cells stably transfected with the rat brain IIA sodium channel with high affinity(K_i 9 nM), as well as agonist-stimulated ²²Na uptake in this cell line. WIN 17317-3 interacts similarlywith skeletal muscle sodium channels but is a weaker inhibitor of the cardiac sodium channel. Together,these results demonstrate that WIN 17317-3 is a new, high-affinity, subtype-selective ligand for sodiumchannels and is a potent blocker of brain IIA sodium channels.