HOW DIETARY N-3 FATTY ACIDS PREVENT FATAL ARRHYTHMIAS

具体目的：我们已经证明，鱼油中的n-3多不饱和脂肪酸（PUFAs）可以防止心源性猝死，就像局部麻醉剂一样，抑制快速的电压依赖性Na+电流（即，电压依赖性需要更负的静息膜电位关闭并使Na+通道恢复到静息、可激活状态）。目的1。确定这种效应的电压敏感性是否足以抑制心脏部分去极化区的动作电位，而不影响保留其正常辞职膜电位的非缺血性心肌细胞。如果是这样，这可以解释n-3 PUFAS抑制INa在缺血诱导的心源性猝死中的作用。目标2。为了确定在人胚胎细胞系HEK 293t中，表达人心肌钠通道α亚基（h1 α），如果D-1， S6-假定的batrachotoxin （BTX）结合位点的位置和D-IV， S6-假定的局部麻醉（LA）受体的位置的点氨基酸突变阻断n-3PUFAs对Na+通道的作用。Las和n-3 PUFAs作用的相似性表明：a)两者都通过非竞争性抑制从Na+通道α -亚基激活状态的结合位点取代了BTX（一种强效的心脏和神经毒性物质）。B)两者都通过延长Na+通道的失活状态来抑制INa。C)两者都是有效的抗心律失常药物。D-IV， S6是LA受体的推测位点，D-I， S6是BTX的结合位点。α -亚基的这两个区域的单个氨基酸突变会使通道对BTX不敏感，并影响LA对Na通道的作用。这些研究将有助于了解n-3 PUFAs如何在分子水平上抑制心肌细胞中的INa。这种作用对于这些n-3 PUFAs预防缺血性致死性室性心律失常是重要的。每年有25万美国人，全世界有数百万人死于心脏性猝死，目前没有安全有效的预防或治疗方法，pufa的这一行动具有潜在的巨大公共卫生效益。

Specific Aims: We have shown that the n-3 polyunsaturated fatty acids (PUFAs) in fish oils, which prevent sudden cardiac death, like local anesthetics, inhibit the fast, voltage dependent Na+ currents (i.e., a voltage-dependent need for a more negative resting membrane potential to close and return the Na+ channels to a resting, activatable state). Aim 1. Too determine if the voltage sensitivity of this effect is sufficient to inhibit action potentials in partially depolarized zones of the heart, but not affect non-ischemic cardiomyocytes that retain their normal resign membrane potentials. If so, this could explain the role of the inhibition of INa by n-3 PUFAS in ischemia-induced sudden cardiac death. Aim 2. To determine in a human embryonic cell line, HEK 293t, expressing alpha-subunits of the human myocardial sodium channel (hH1alpha), if point amino acid mutations in D-1, S6- the location of the putative batrachotoxin (BTX) binding site- and D-IV, S6- the location of the putative local anesthetic (LA) receptor-block the action of the n-3PUFAs on the Na+ channel grating process. Similarities between effects of Las and n-3 PUFAs indicates this to be likely: a) Both displace BTX, a potent cardiac and neural poison, from its binding site on the activated state of the Na+ channel alpha- subunit by non-competitive inhibition. B) Both inhibit INa by prolonging the inactivated state of the Na+ channel. C) Both are potent anti-arrhythmic agents. D-IV, S6 is the putative site of the LA receptor an D-I, S6 is the site of BTX binding. A single amino acid mutation in these two regions of the alpha-subunit renders the channel insensitive to BTX and affect LA action on the Na channel. These studies will add to understanding of how n-3 PUFAs act at a molecular level to inhibit the INa in cardiac myocytes. This effect is important for the preention by these n-3 PUFAs of ischemia-induced fatal ventricular arrhythmias. With 250,000 Americans, and millions more world wide, dying annually from cardiac sudden death for which there is no current safe and effective prevention or therapy, this action of the PUFAs has potentially great public health benefit.