Veress Roland, Baranyai Dóra, Hegyi Bence, Kistamás Kornél, Dienes Csaba, Magyar János, Bányász Tamás, Nánási Péter P, Szentandrássy Norbert, Horváth Balázs
a Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
b Department of Pharmacology, University of California at Davis, Davis, CA 95616, USA.
Can J Physiol Pharmacol. 2018 Oct;96(10):1022-1029. doi: 10.1139/cjpp-2018-0049. Epub 2018 May 28.
The role of transient receptor potential melastatin 4 (TRPM4) channels has been frequently tested using their inhibitor 9-phenanthrol in various cardiac preparations; however, the selectivity of the compound is uncertain. Therefore, in the present study, the concentration-dependent effects of 9-phenanthrol on major ionic currents were studied in canine isolated ventricular cells using whole-cell configuration of the patch-clamp technique and 10 mM BAPTA-containing pipette solution to prevent the Ca-dependent activation of TRPM4 channels. Transient outward (I), rapid delayed rectifier (I), and inward rectifier (I) K currents were suppressed by 10 and 30 μM 9-phenanthrol with the blocking potency for I < I < I and partial reversibility. L-type Ca current was not affected up to the concentration of 30 μM. In addition, a steady outward current was detected at voltages positive to -40 mV in 9-phenanthrol, which was larger at more positive voltages and larger 9-phenanthrol concentrations. Action potentials were recorded using microelectrodes. Maximal rate of depolarization, phase-1 repolarization, and terminal repolarization were decreased and the plateau potential was depressed by 9-phenanthrol (3-30 μM), congruently with the observed alterations of ionic currents. Significant action potential prolongation was observed by 9-phenanthrol in the majority of the studied cells, but only at 30 μM concentration. In conclusion, 9-phenanthrol is not selective to TRPM4 channels in canine ventricular myocardium; therefore, its application as a TRPM4 blocker can be appropriate only in expression systems but not in native cardiac cells.
瞬时受体电位褪黑素4（TRPM4）通道的作用已在各种心脏制剂中频繁使用其抑制剂9-菲咯啉进行测试；然而，该化合物的选择性尚不确定。因此，在本研究中，使用膜片钳技术的全细胞配置和含10 mM BAPTA的移液管溶液，以防止TRPM4通道的钙依赖性激活，研究了9-菲咯啉对犬离体心室细胞主要离子电流的浓度依赖性影响。10和30 μM的9-菲咯啉可抑制瞬时外向电流（I）、快速延迟整流电流（I）和内向整流电流（I），对I的阻断效力小于I小于I，且具有部分可逆性。高达30 μM的浓度对L型钙电流无影响。此外，在9-菲咯啉中，在电压高于-40 mV时检测到稳定的外向电流，在更正的电压和更高的9-菲咯啉浓度下更大。使用微电极记录动作电位。9-菲咯啉（3-30 μM）可降低最大去极化速率、1期复极化和终末复极化，并降低平台电位，这与观察到的离子电流变化一致。在大多数研究细胞中，9-菲咯啉可显著延长动作电位，但仅在30 μM浓度时。总之，9-菲咯啉对犬心室心肌中的TRPM4通道没有选择性；因此，它作为TRPM4阻滞剂仅适用于表达系统，而不适用于天然心脏细胞。
