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动作电位通常因刺激提高了 ''Vm'' 等因素使轴丘足够去极化而发生。这种去极化通常是由细胞注入额外的钠离子等阳离子引起的；这些阳离子有多种来源，如化学突触、感觉神经元或起搏电位。

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对于处于静息状态的神经元来说，细胞外液的钠离子和氯离子浓度高于细胞内液中，而细胞内液的钾离子浓度高于细胞外液。使离子从高浓度向低浓度移动的浓度差，以及静电作用（相反电荷的吸引）决定离子流出或流入神经元。由于细胞的 K+ 外流，神经元内部相对于外部带负电。神经元的细胞膜对 K+ 的渗透性比其他离子更强，使得这种离子能够选择性地顺着浓度梯度流出细胞。这种浓度梯度以及神经元膜上的钾离子泄漏通道（potassium leak channel）导致钾离子外流，使静息电位接近 ''E''K ≈ -75 mV。由于钠离子在细胞外的浓度较高，当钠离子通道打开时，浓度差和电位差都驱使其进入细胞。去极化打开了细胞膜上的钠通道和钾通道，允许离子分别流入和流出轴突。如果去极化很小（比方说，把 ''Vm'' 从 -70 mV 增加到 -60 mV），外向的钾电流大过内向的钠电流，膜复极化回到正常的静息电位 -70 mV 左右。然而，当去极化足够大时，内向钠电流的增加大于外向钾电流，出现了失控（正反馈）现象：内向钠电流越大， ''Vm'' 越是升高，其反过来又进一步增加内向钠电流。足够强的去极化（ ''Vm'' 的增加）使电压敏感的钠通道开放，钠的渗透性增加使 ''Vm'' 趋向钠平衡电位 ''E''Na ≈ +55 mV。电位增加进而导致更多的钠离子通道打开，这使得 ''Vm'' 更趋近 ''E''Na。这种正反馈持续到钠离子通道完全打开，''Vm'' 接近 ''E''Na。''Vm'' 和钠通透性的骤然上升与动作电位的上升相是对应的。

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对于处于静息状态的神经元来说，细胞外液的钠离子和氯离子浓度高于细胞内液中，而细胞内液的钾离子浓度高于细胞外液。使离子从高浓度向低浓度移动的浓度差，以及静电作用（相反电荷的吸引）决定离子流出或流入神经元。由于细胞的 K+ 外流，神经元内部相对于外部带负电。神经元的细胞膜对 K+ 的渗透性比其他离子更强，使得这种离子能够选择性地顺着浓度梯度流出细胞。这种浓度梯度以及神经元膜上的钾离子泄漏通道（potassium leak channel）导致钾离子外流，使静息电位接近 ''E''K ≈ -75 mV。由于钠离子在细胞外的浓度较高，当钠离子通道打开时，浓度差和电位差都驱使其进入细胞。去极化打开了细胞膜上的钠通道和钾通道，允许离子分别流入和流出轴突。如果去极化很小（比方说，把 ''Vm'' 从 -70 mV 增加到 -60 mV），外向的钾电流大过内向的钠电流，膜复极化回到正常的静息电位 -70 mV 左右。然而，当去极化足够大时，内向钠电流的增加大于外向钾电流，出现了失控（正反馈）现象：内向钠电流越大， ''Vm'' 越是升高，其反过来又进一步增加内向钠电流。足够强的去极化（ ''Vm'' 的增加）使电压敏感的钠通道开放，钠的渗透性增加使 ''Vm'' 趋向钠平衡电位 ''E''Na ≈ +55 mV。电位增加进而导致更多的钠离子通道打开，这使得 ''Vm'' 更趋近 ''E''Na。这种正反馈持续到钠离子通道完全打开，''Vm'' 接近 ''E''Na。''Vm'' 和钠通透性的骤然上升与动作电位的上升相是对应的。

这种失控状态的临界阈值电位通常在 -45 mV 左右，但这取决于轴突最近的活动。刚发放过动作电位的细胞不能立即发放新的动作电位，因为 Na+ 通道还没有从失活状态恢复过来。不能发放新的动作电位的这段时间叫做绝对不应期（''absolute refractory period''）。在部分的离子通道恢复后，轴突可以被刺激产生新的动作电位，但需要更高的阈值电位，即需要更强的去极化，比如 -30 mV。很难触发动作电位的时期称为相对不应期（''relative refractory period''）。

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===髓鞘和跳跃式传导===

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为了在神经系统中快速高效地传递电信号，某些神经元的轴突上覆有髓鞘（myelin sheath）。髓鞘是多层膜，将轴突逐段包裹起来，段的间隔被称为郎飞结。它由专门的细胞产生：周围神经系统中是施万细胞（[[Schwann cell]]s），中央神经系统中是少突胶质细胞（[[oligodendrocyte]]s）。髓鞘减少了膜电容，并增加结间段的膜电阻，从而让动作电位在郎飞结之间快速、跳跃式的移动。<ref name="Zalc" group="lower-alpha">{{cite journal | vauthors = Zalc B | title = The acquisition of myelin: a success story | journal = Novartis Foundation Symposium | volume = 276 | pages = 15–21; discussion 21–5, 54–7, 275–81 | year = 2006 | pmid = 16805421 | doi = 10.1002/9780470032244.ch3 | isbn = 978-0-470-03224-4 | series = Novartis Foundation Symposia }}</ref><ref name="S. Poliak & E. Peles" group="lower-alpha">{{cite journal | vauthors = Poliak S, Peles E | title = The local differentiation of myelinated axons at nodes of Ranvier | journal = Nature Reviews. Neuroscience | volume = 4 | issue = 12 | pages = 968–80 | date = December 2003 | pmid = 14682359 | doi = 10.1038/nrn1253 | s2cid = 14720760 }}</ref><ref name=":2" group="lower-alpha">{{cite journal | vauthors = Simons M, Trotter J | title = Wrapping it up: the cell biology of myelination | journal = Current Opinion in Neurobiology | volume = 17 | issue = 5 | pages = 533–40 | date = October 2007 | pmid = 17923405 | doi = 10.1016/j.conb.2007.08.003 | s2cid = 45470194 }}</ref> 髓鞘形成（myelination）主要存在于脊椎动物，不过一些无脊椎动物也有类似的系统，比如某些种类的虾。<ref name=":3" group="lower-alpha">{{cite journal | vauthors = Xu K, Terakawa S | title = Fenestration nodes and the wide submyelinic space form the basis for the unusually fast impulse conduction of shrimp myelinated axons | journal = The Journal of Experimental Biology | volume = 202 | issue = Pt 15 | pages = 1979–89 | date = August 1999 | doi = 10.1242/jeb.202.15.1979 | pmid = 10395528 | url = http://jeb.biologists.org/cgi/pmidlookup?view=long&pmid=10395528 }}</ref> 脊椎动物中并不是所有的神经元都有髓鞘；例如，组成自主神经系统的神经元的轴突一般都没有髓鞘。髓鞘阻止了离子从髓鞘包裹的轴突部位出入。一般地，髓鞘增加了动作电位的传导速度，使其能效更高。不管是否跳跃，动作电位的平均传导速度范围从 1 米每秒（m/s）到 100 m/s 以上，一般而言，随轴突直径的增大而增大。<ref name="hursh_1939" group="lower-alpha">{{cite journal | vauthors = Hursh JB | year = 1939 | title = Conduction velocity and diameter of nerve fibers | journal = American Journal of Physiology | volume = 127 | pages = 131–39| doi = 10.1152/ajplegacy.1939.127.1.131 }}</ref>

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为了在神经系统中快速高效地传递电信号，某些神经元的轴突上覆有髓鞘（myelin sheath）。髓鞘是多层膜，将轴突逐段包裹起来，段的间隔被称为郎飞结。它由专门的细胞产生：周围神经系统中是施万细胞（[[Schwann cell]]s），中央神经系统中是少突胶质细胞（[[oligodendrocyte]]s）。髓鞘减少了膜电容，并增加结间段的膜电阻，从而让动作电位在郎飞结之间快速、跳跃式的移动。<ref name="Zalc" group="lower-alpha">{{cite journal | vauthors = Zalc B | title = The acquisition of myelin: a success story | journal = Novartis Foundation Symposium | volume = 276 | pages = 15–21; discussion 21–5, 54–7, 275–81 | year = 2006 | pmid = 16805421 | doi = 10.1002/9780470032244.ch3 | isbn = 978-0-470-03224-4 | series = Novartis Foundation Symposia }}</ref><ref name="S. Poliak & E. Peles" group="lower-alpha">{{cite journal | vauthors = Poliak S, Peles E | title = The local differentiation of myelinated axons at nodes of Ranvier | journal = Nature Reviews. Neuroscience | volume = 4 | issue = 12 | pages = 968–80 | date = December 2003 | pmid = 14682359 | doi = 10.1038/nrn1253 | s2cid = 14720760 }}</ref><ref name=":2" group="lower-alpha">{{cite journal | vauthors = Simons M, Trotter J | title = Wrapping it up: the cell biology of myelination | journal = Current Opinion in Neurobiology | volume = 17 | issue = 5 | pages = 533–40 | date = October 2007 | pmid = 17923405 | doi = 10.1016/j.conb.2007.08.003 | s2cid = 45470194 }}</ref> 髓鞘形成（myelination）主要存在于脊椎动物，不过一些无脊椎动物也有类似的系统，比如某些种类的虾。<ref name=":3" group="lower-alpha">{{cite journal | vauthors = Xu K, Terakawa S | title = Fenestration nodes and the wide submyelinic space form the basis for the unusually fast impulse conduction of shrimp myelinated axons | journal = The Journal of Experimental Biology | volume = 202 | issue = Pt 15 | pages = 1979–89 | date = August 1999 | doi = 10.1242/jeb.202.15.1979 | pmid = 10395528 | url = http://jeb.biologists.org/cgi/pmidlookup?view=long&pmid=10395528 }}</ref> 脊椎动物中并不是所有的神经元都有髓鞘；例如，组成自主神经系统的神经元的轴突一般都没有髓鞘。髓鞘阻止了离子从髓鞘包裹的轴突部位出入。一般地，髓鞘增加了动作电位的传导速率，使其能效更高。不管是否跳跃，动作电位的平均传导速率范围从 1 米每秒（m/s）到 100 m/s 以上，一般而言，随轴突直径的增大而增大。<ref name="hursh_1939" group="lower-alpha">{{cite journal | vauthors = Hursh JB | year = 1939 | title = Conduction velocity and diameter of nerve fibers | journal = American Journal of Physiology | volume = 127 | pages = 131–39| doi = 10.1152/ajplegacy.1939.127.1.131 }}</ref>

动作电位不能在有髓鞘的轴突段的膜上传播。不过，电流经细胞质传输，足以使后面的一两个郎飞结去极化。就是说，一个郎飞结的动作电位产生的离子电流在下一个郎飞结引起另一个动作电位；动作电位的这种看似在郎飞结之间“跳跃”被称为跳跃式传导。跳跃式传导的机制在 1925 年就由 Ralph Lillie 提出，<ref name=":4" group="lower-alpha">{{cite journal | vauthors = Lillie RS | title = Factors Affecting Transmission and Recovery in the Passive Iron Nerve Model | journal = The Journal of General Physiology | volume = 7 | issue = 4 | pages = 473–507 | date = March 1925 | pmid = 19872151 | pmc = 2140733 | doi = 10.1085/jgp.7.4.473 }} See also {{harvnb|Keynes|Aidley|1991|p=78}}</ref> 但其首个实验证据来自 Ichiji Tasaki <ref name="tasaki_1939" group="lower-alpha">{{cite journal | vauthors = Tasaki I | year = 1939 | title = Electro-saltatory transmission of nerve impulse and effect of narcosis upon nerve fiber | journal = Am. J. Physiol. | volume = 127 | pages = 211–27| doi = 10.1152/ajplegacy.1939.127.2.211 }}</ref> 和 Taiji Takeuchi <ref name="tasaki_1941_1942_1959" group="lower-alpha">{{cite journal | vauthors = Tasaki I, Takeuchi T | year = 1941 | title = Der am Ranvierschen Knoten entstehende Aktionsstrom und seine Bedeutung für die Erregungsleitung | journal = Pflügers Archiv für die gesamte Physiologie | volume = 244 | pages = 696–711 | doi = 10.1007/BF01755414 | issue = 6 | s2cid = 8628858 }} * {{cite journal | vauthors = Tasaki I, Takeuchi T | year = 1942 | title = Weitere Studien über den Aktionsstrom der markhaltigen Nervenfaser und über die elektrosaltatorische Übertragung des nervenimpulses | journal = Pflügers Archiv für die gesamte Physiologie | volume = 245 | pages = 764–82 | doi = 10.1007/BF01755237 | issue = 5 | s2cid = 44315437 }}</ref><ref name=":12">Tasaki, I in {{harvnb|Field|1959|pp=75–121}}</ref> 以及 Andrew Huxley 和 Robert Stämpflii。<ref name="huxley_staempfli_1949_1951" group="lower-alpha">{{cite journal | vauthors = Huxley AF, Stämpfli R | title = Evidence for saltatory conduction in peripheral myelinated nerve fibres | journal = The Journal of Physiology | volume = 108 | issue = 3 | pages = 315–39 | date = May 1949 | pmid = 16991863 | pmc = 1392492 | doi = 10.1113/jphysiol.1949.sp004335 | author-link1 = Andrew Huxley }} * {{cite journal | vauthors = Huxley AF, Stampfli R | title = Direct determination of membrane resting potential and action potential in single myelinated nerve fibers | journal = The Journal of Physiology | volume = 112 | issue = 3–4 | pages = 476–95 | date = February 1951 | pmid = 14825228 | pmc = 1393015 | doi = 10.1113/jphysiol.1951.sp004545 | author-link1 = Andrew Huxley }}</ref> 而在无髓鞘的轴突，动作电位在紧邻的膜上引起另一个动作电位，并像波一样沿着轴突不断地移动。

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[[Image:Conduction velocity and myelination.png|thumb|right|300px|~~猫的有髓鞘和无髓鞘轴突的传导速度的比较。有髓鞘神经元的传导速度~~ ''v'' 与轴突直径 ''d'' 大致呈线性变化（即 ''v'' ∝ ''d''），<ref name="hursh_1939" group="lower-alpha" /> 而无髓鞘神经元的速度大致与平方根呈线性变化（''v'' ∝√''d''）。<ref name="rushton_1951" group="lower-alpha">{{cite journal | vauthors = Rushton WA | title = A theory of the effects of fibre size in medullated nerve | journal = The Journal of Physiology | volume = 115 | issue = 1 | pages = 101–22 | date = September 1951 | pmid = 14889433 | pmc = 1392008 | doi = 10.1113/jphysiol.1951.sp004655 | author-link = W. A. H. Rushton }}</ref> 红色和蓝色曲线是实验数据的拟合，而虚线是其理论外推。|链接=Special:FilePath/Conduction_velocity_and_myelination.png]]

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[[Image:Conduction velocity and myelination.png|thumb|right|300px|猫的有髓鞘和无髓鞘轴突的传导速率的比较。有髓鞘神经元的传导速率 ''v'' 与轴突直径 ''d'' 大致呈线性变化（即 ''v'' ∝ ''d''），<ref name="hursh_1939" group="lower-alpha" /> 而无髓鞘神经元的速度大致与平方根呈线性变化（''v'' ∝√''d''）。<ref name="rushton_1951" group="lower-alpha">{{cite journal | vauthors = Rushton WA | title = A theory of the effects of fibre size in medullated nerve | journal = The Journal of Physiology | volume = 115 | issue = 1 | pages = 101–22 | date = September 1951 | pmid = 14889433 | pmc = 1392008 | doi = 10.1113/jphysiol.1951.sp004655 | author-link = W. A. H. Rushton }}</ref> 红色和蓝色曲线是实验数据的拟合，而虚线是其理论外推。|链接=Special:FilePath/Conduction_velocity_and_myelination.png]]

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~~髓鞘具有两个重要的优势：传导速度快和能效高。粗于一个最小直径（大约~~ 1 ~~微米）的轴突，髓鞘通常能让动作电位的传导速度增加十倍。~~<ref name="hartline_2007" group="lower-alpha">{{cite journal | vauthors = Hartline DK, Colman DR | title = Rapid conduction and the evolution of giant axons and myelinated fibers | journal = Current Biology | volume = 17 | issue = 1 | pages = R29-35 | date = January 2007 | pmid = 17208176 | doi = 10.1016/j.cub.2006.11.042 | s2cid = 10033356 | doi-access = free }}</ref> ~~反之，相同的传导速度，有髓鞘的神经纤维比无髓的更细。例如，有髓鞘的蛙轴突和无髓鞘的乌贼巨轴突（squid~~ giant ~~axon）的动作电位传导速度大致相同（25~~ 米/秒），但是青蛙的轴突直径要小 30 倍，横截面积要小 1000 倍。此外，因为离子电流被局限于郎飞结，离子的跨膜“泄漏”要少得多，节省了新陈代谢能量。考虑到人类神经系统消耗大约 20% 的身体代谢能量，这种节省有显著的选择优势（[[natural selection|selective advantage]]）。<ref name="hartline_2007" group="lower-alpha" />

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髓鞘具有两个重要的优势：传导速率快和能效高。粗于一个最小直径（大约 1 微米）的轴突，髓鞘通常能让动作电位的传导速率增加十倍。<ref name="hartline_2007" group="lower-alpha">{{cite journal | vauthors = Hartline DK, Colman DR | title = Rapid conduction and the evolution of giant axons and myelinated fibers | journal = Current Biology | volume = 17 | issue = 1 | pages = R29-35 | date = January 2007 | pmid = 17208176 | doi = 10.1016/j.cub.2006.11.042 | s2cid = 10033356 | doi-access = free }}</ref> 反之，相同的传导速率，有髓鞘的神经纤维比无髓的更细。例如，有髓鞘的蛙轴突和无髓鞘的乌贼巨轴突（squid giant axon）的动作电位传导速率大致相同（25 米/秒），但是青蛙的轴突直径要小 30 倍，横截面积要小 1000 倍。此外，因为离子电流被局限于郎飞结，离子的跨膜“泄漏”要少得多，节省了新陈代谢能量。考虑到人类神经系统消耗大约 20% 的身体代谢能量，这种节省有显著的选择优势（[[natural selection|selective advantage]]）。<ref name="hartline_2007" group="lower-alpha" />

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髓鞘包裹的轴突节段的长度对跳跃式传导的成功至关重要。它们应尽可能长，以最大限度地提高传导速度，但不能太长，以至于传过去的信号太弱，无法在下一个郎飞结触发动作电位。在自然界中，有髓鞘节段通常足够长，使信号被动传播至少两个结点而仍有足够的强度在第二、三结点触发动作电位。因此，跳跃式传导的安全系数很高，可以绕过损伤的郎飞结继续传播。然而，动作电位可能在安全系数较低的某些位置过早终止，即使在无髓神经元中也是如此；一个常见的例子是轴突分支成两个轴突的分支点。

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髓鞘包裹的轴突节段的长度对跳跃式传导的成功至关重要。它们应尽可能长，以最大限度地提高传导速率，但不能太长，以至于传过去的信号太弱，无法在下一个郎飞结触发动作电位。在自然界中，有髓鞘节段通常足够长，使信号被动传播至少两个结点而仍有足够的强度在第二、三结点触发动作电位。因此，跳跃式传导的安全系数很高，可以绕过损伤的郎飞结继续传播。然而，动作电位可能在安全系数较低的某些位置过早终止，即使在无髓神经元中也是如此；一个常见的例子是轴突分支成两个轴突的分支点。

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~~有些疾病会降解髓鞘，破坏跳跃式传导，降低动作电位的传导速度。~~<ref name=":5" group="lower-alpha">{{cite journal | vauthors = Miller RH, Mi S | title = Dissecting demyelination | journal = Nature Neuroscience | volume = 10 | issue = 11 | pages = 1351–4 | date = November 2007 | pmid = 17965654 | doi = 10.1038/nn1995 | s2cid = 12441377 }}</ref> 其中最被人所知的是多发性硬化症（multiple sclerosis），髓鞘的降解削弱协调运动。<ref name=":13">Waxman, SG in {{harvnb|Waxman|2007|loc=''Multiple Sclerosis as a Neurodegenerative Disease'', pp. 333–346.}}</ref>

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有些疾病会降解髓鞘，破坏跳跃式传导，降低动作电位的传导速率。<ref name=":5" group="lower-alpha">{{cite journal | vauthors = Miller RH, Mi S | title = Dissecting demyelination | journal = Nature Neuroscience | volume = 10 | issue = 11 | pages = 1351–4 | date = November 2007 | pmid = 17965654 | doi = 10.1038/nn1995 | s2cid = 12441377 }}</ref> 其中最被人所知的是多发性硬化症（multiple sclerosis），髓鞘的降解削弱协调运动。<ref name=":13">Waxman, SG in {{harvnb|Waxman|2007|loc=''Multiple Sclerosis as a Neurodegenerative Disease'', pp. 333–346.}}</ref>

===电缆学说===

[[File:Cable theory Neuron RC circuit v3.svg|thumb|300x300px|电缆理论对神经元纤维的简化图。连接的 RC 电路对应于被动的神经突相邻的节段。（与胞内阻抗 ''ri'' 对应的）胞外阻抗 ''re'' 未显示，因其通常小到可以忽略不计；细胞外液可以认为是处处电位相等。|链接=Special:FilePath/Cable_theory_Neuron_RC_circuit_v3.svg]]

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\tau \frac{\partial V}{\partial t} = \lambda^2 \frac{\partial^2 V}{\partial x^2} - V

</math>

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where ''V''（''x'', ''t''） is the voltage across the membrane at a time ''t'' and a position ''x'' along the length of the neuron, and where λ and τ are the characteristic length and time scales on which those voltages decay in response to a stimulus. Referring to the circuit diagram on the right, these scales can be determined from the resistances and capacitances per unit length.{{sfn|Purves|Augustine|Fitzpatrick|Hall|2008|pp=52–53}}

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其中 ''V(x'', ''t)'' 是时间 ''t'' 和沿神经元长度的位置 ''x'' 的跨膜电压，其中 λ 和 τ 是特征长度和时间尺度，对刺激的反应的电位以这些尺度发生衰减。参考右边的电路图，这些尺度可以通过单位长度的电阻和电容来确定。

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其中 ''V(x'', ''t)'' 是时间 ''t'' 和沿神经元长度的位置 ''x'' 的跨膜电压，其中 λ 和 τ ~~是特征长度和时间尺度，对刺激的反应电位以这些尺度发生衰减。参考右边的电路图，这些尺度可以通过单位长度的电阻和电容来确定。~~

:<math>

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</math>

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这些时间尺度和长度尺度可用于理解无髓鞘纤维中传导速率对神经元直径的依赖关系。比如，时间尺度 τ 随着膜电阻 ''rm'' 和膜电容 ''cm'' 的增大而增大。随着电容的增加，（根据公式 [[capacitance|''Q'' = ''CV'']]）必须转移更多的电荷才能产生给定的跨膜电压；随着电阻的增加，每单位时间转移的电荷越少，则越慢恢复平衡。同样，如果轴突的单位长度的内阻 ''ri'' 较小（比如由于半径较大），空间衰减长度 λ 变长，动作电位的传导速率应该增加。如果跨膜电阻 ''rm'' 增大，减少平均跨膜“泄漏”电流，同样导致 λ 变长，增加了传导速率。

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These time and length-scales can be used to understand the dependence of the conduction velocity on the diameter of the neuron in unmyelinated fibers. For example, the time-scale τ increases with both the membrane resistance ''rm'' and capacitance ''cm''. As the capacitance increases, more charge must be transferred to produce a given transmembrane voltage （by [[capacitance|the equation ''Q'' = ''CV'']]）; as the resistance increases, less charge is transferred per unit time, making the equilibration slower. In a similar manner, if the internal resistance per unit length ''ri'' is lower in one axon than in another （e.g., because the radius of the former is larger）, the spatial decay length λ becomes longer and the [[conduction velocity]] of an action potential should increase. If the transmembrane resistance ''rm'' is increased, that lowers the average "leakage" current across the membrane, likewise causing ''λ'' to become longer, increasing the conduction velocity.

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~~这些时间尺度和长度尺度可以用来理解无髓鞘纤维中传导速度依赖于神经元直径。比如，时间尺度~~ τ 随着膜电阻 ''rm'' 和膜电容 ''cm'' 的增大而增大。随着电容的增加，（根据公式 [[capacitance|''Q'' = ''CV'']]~~）必须转移更多的电荷才能产生给定的跨膜电压；随着电阻的增加，每单位时间转移的电荷越少，越慢恢复平衡。同样，如果一个轴突的单位长度~~ ''ri'' ~~低于另一个轴突（比如，因为前者的半径较大），空间衰减长度~~ λ ~~变长，动作电位的传导速度应该增加。如果跨膜电阻~~ ''rm'' ~~增大，降低平均跨膜“泄漏”电流，同样导致~~ λ ~~变长，增加了传导速度。~~

==动作电位的终止==

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However, the flytrap doesn't close after one trigger. Instead, it requires the activation of 2 or more hairs.<ref name=":1" /><ref name=":2" /> If only one hair is triggered, it throws the activation as a false positive. Further, the second hair must be activated within a certain time interval （0.75 s - 40 s） for it to register with the first activation.<ref name=":2" /> Thus, a buildup of calcium starts and slowly falls from the first trigger. When the second action potential is fired within the time interval, it reaches the Calcium threshold to depolarize the cell, closing the trap on the prey within a fraction of a second.<ref name=":2" />

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然而，捕蝇草不会在一次触发后闭合，而是需要激活 2 ~~根或更多的毛。~~<ref name=":1" /><ref name=":2" /> 如果只有一根毛被触发，这个激活会被视为假阳性。而且第二根毛必须在一定的时间间隔（0.75 s - 40 s）内被激活，才能将其与第一次激活一起记录。<ref name=":2" /> 因此，第一次触发开始钙的积累从并且然后慢慢下降。当第二个动作电位在时间间隔内被激发时，它达到钙阈值使细胞去极化，在几分之一秒内关闭捕获物的陷阱。<ref name=":2" />

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然而，捕蝇草不会在一次触发后闭合，而是需要激活 2 根或更多的感觉毛。<ref name=":1" /><ref name=":2" /> 如果只有一根毛被触发，这个激活会被视为假阳性。而且第二根毛必须在一定的时间间隔（0.75 s - 40 s）内被激活，才能将其与第一次激活一起记录。<ref name=":2" /> 因此，第一次触发开始钙的积累从并且然后慢慢下降。当第二个动作电位在时间间隔内被激发时，它达到钙阈值使细胞去极化，在几分之一秒内关闭捕获物的陷阱。<ref name=":2" />

Together with the subsequent release of positive potassium ions the action potential in plants involves an [[osmotic]] loss of salt （KCl）. Whereas, the animal action potential is osmotically neutral because equal amounts of entering sodium and leaving potassium cancel each other osmotically. The interaction of electrical and osmotic relations in plant cells<ref name="Gradmann_1998" group="lower-alpha">{{cite journal | vauthors = Gradmann D, Hoffstadt J | title = Electrocoupling of ion transporters in plants: interaction with internal ion concentrations | journal = The Journal of Membrane Biology | volume = 166 | issue = 1 | pages = 51–9 | date = November 1998 | pmid = 9784585 | doi = 10.1007/s002329900446 | s2cid = 24190001 }}</ref> appears to have arisen from an osmotic function of electrical excitability in a common unicellular ancestors of plants and animals under changing salinity conditions. Further, the present function of rapid signal transmission is seen as a newer accomplishment of [[metazoan]] cells in a more stable osmotic environment.<ref name="Gradmann_1980">

Gradmann, D; Mummert, H in {{harvnb|Spanswick|Lucas|Dainty|1980|loc=''Plant action potentials'', pp. 333–344.}}</ref> It is likely that the familiar signaling function of action potentials in some vascular plants （e.g. ''[[Mimosa pudica]]''） arose independently from that in metazoan excitable cells.

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随着随后释放的阳性钾离子，动作电位在植物中涉及盐（KCl）渗透损失。然而，动物的动作电位是渗透中性的，因为等量的钠进入和钾离开相互抵消渗透。植物细胞<ref name="Gradmann_1998" group="lower-alpha" />中电和渗透关系的相互作用似乎起源于盐度变化条件下动植物共同的单细胞祖先的电兴奋渗透作用。此外，目前的快速信号传递功能被认为是后生动物细胞在更稳定的渗透环境中更新的成就.<ref name="Gradmann_1980" /> 。在一些维管植物中，动作电位的常见信号功能可能是。含羞草（Mimosa putica）是独立于后生动物兴奋细胞而产生的。

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随着随后释放的阳性钾离子，动作电位在植物中涉及盐（KCl）渗透损失。然而，动物的动作电位是渗透中性的，因为等量的钠内流和钾外流相互抵消渗透。植物细胞<ref name="Gradmann_1998" group="lower-alpha" />中电和渗透关系的相互作用似乎起源于盐度变化条件下动植物共同的单细胞祖先的电兴奋渗透作用。此外，目前的快速信号传递功能被认为是后生动物细胞在更稳定的渗透环境中更新的成就.<ref name="Gradmann_1980" /> 。在一些维管植物中，动作电位的常见信号功能可能是。含羞草（Mimosa putica）是独立于后生动物兴奋细胞而产生的。

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Unlike the rising phase and peak, the falling phase and after-hyperpolarization seem to depend primarily on cations that are not calcium. To initiate repolarization, the cell requires movement of potassium out of the cell through passive transportation on the membrane. This differs from neurons because the movement of potassium does not dominate the decrease in membrane potential; In fact, to fully repolarize, a plant cell requires energy in the form of ATP to assist in the release of hydrogen from the cell – utilizing a transporter commonly known as H+-ATPase.<ref name="Opritov">Opritov, V A, et al. “Direct Coupling of Action Potential Generation in Cells of a Higher Plant (Cucurbita Pepo) with the Operation of an Electrogenic Pump.” ''Russian Journal of Plant Physiology'', vol. 49, no. 1, 2002, pp. 142–147.</ref><ref name=":2" />

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不同于上升相和峰值，下降相和后超极化似乎主要依赖于非钙离子的阳离子。为了启动复极化，细胞需要将钾离子通过细胞膜上的结构被动运输到胞外。事实上，为了完全再极化，植物细胞需要能量以 ATP ~~的形式帮助细胞释放氢-利用一种通常被称为~~ H+-~~ATPase 酶的转运蛋白。~~<ref name="Opritov" /><ref name=":2" />

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不同于上升相和峰值，下降相和后超极化似乎主要依赖于非钙离子的阳离子。为了启动复极化，细胞需要将钾离子通过细胞膜上的被动运输机制输出到胞外。不像神经元中钾离子的移动决定膜电位下降，植物细胞完全复极化时，需要消耗 ATP 能，帮助细胞利用称为氢钾 ATP 酶（ H+-ATPase）的转运蛋白释放氢。<ref name="Opritov">Opritov, V A, et al. “Direct Coupling of Action Potential Generation in Cells of a Higher Plant (Cucurbita Pepo) with the Operation of an Electrogenic Pump.” ''Russian Journal of Plant Physiology'', vol. 49, no. 1, 2002, pp. 142–147.</ref><ref name=":2" />

==分类学分布和进化优势==

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Scientists of the 19th century studied the propagation of electrical signals in whole [[nerve]]s （i.e., bundles of [[neuron]]s） and demonstrated that nervous tissue was made up of [[cell (biology)|cells]], instead of an interconnected network of tubes （a ''reticulum''）.{{sfnm|1a1=Brazier|1y=1961|2a1=McHenry|2a2=Garrison|2y=1969|3a1=Worden|3a2=Swazey|3a3=Adelman|3y=1975}} [[Carlo Matteucci]] followed up Galvani's studies and demonstrated that [[cell membrane]]s had a voltage across them and could produce [[direct current]]. Matteucci's work inspired the German physiologist, [[Emil du Bois-Reymond]], who discovered the action potential in 1843.<ref name=":21">{{Cite book|title=Emil du Bois-Reymond : neuroscience, self, and society in nineteenth-century Germany|last=Finkelstein | first = Gabriel Ward | name-list-style = vanc |isbn=9781461950325|location=Cambridge, Massachusetts|oclc=864592470|year = 2013}}</ref> The [[conduction velocity]] of action potentials was first measured in 1850 by du Bois-Reymond's friend, [[Hermann von Helmholtz]].<ref name=":22">[[Kathryn Olesko|Olesko, Kathryn M.]], and Frederic L. Holmes. "Experiment, Quantification and Discovery: Helmholtz's Early Physiological Researches, 1843-50". In ''Hermann von Helmholtz and the Foundations of Nineteenth Century Science'', ed. David Cahan, 50-108. Berkeley; Los Angeles; London: University of California, 1994.</ref> To establish that nervous tissue is made up of discrete cells, the Spanish physician [[Santiago Ramón y Cajal]] and his students used a stain developed by [[Camillo Golgi]] to reveal the myriad shapes of neurons, which they rendered painstakingly. For their discoveries, Golgi and Ramón y Cajal were awarded the 1906 [[Nobel Prize in Physiology or Medicine|Nobel Prize in Physiology]].<ref name="Nobel_1906" group="lower-Greek">{{cite press release | url = http://nobelprize.org/medicine/laureates/1906/index.html | title = The Nobel Prize in Physiology or Medicine 1906 | publisher = The Royal Swedish Academy of Science | year = 1906 | access-date = 2010-02-21 | url-status = live | archive-url = https://web.archive.org/web/20081204190959/http://nobelprize.org/medicine/laureates/1906/index.html | archive-date = 4 December 2008 | df = dmy-all }}</ref> Their work resolved a long-standing controversy in the [[neuroanatomy]] of the 19th century; Golgi himself had argued for the network model of the nervous system.

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19 ~~世纪的科学家研究了电信号在整个神经（即神经元束）中的传播，并证明神经组织是由细胞组成的，而不是一个互相连接的管网（网状结构）。Carlo~~ Matteucci ~~继续伽伐尼的研究，证明细胞膜上有一个电压，可以产生直流电。[[~~Carlo Matteucci~~]] 的工作启发了德国生理学家~~ [[Emil du Bois-Reymond]]~~，后者在1843 年发现了动作电位.~~<ref name=":21" /> ~~。动作电位的传导速度最早是在1850年由 [[~~Hermann von Helmholtz]] 测量的。<ref name=":22" /> ~~为了证明神经组织是由离散的细胞组成的，西班牙物理学家~~ [[Santiago Ramón y Cajal]] ~~和他的学生们使用了~~ Camillo Golgi ~~开发的染色剂显示了无数神经元的形状，他们煞费苦心地进行了绘制。由于他们的发现，Golgi~~ 和 [[Santiago Ramón y Cajal|Ramón y Cajal]] 获得了 1906 年的诺贝尔生理学奖。<ref name="Nobel_1906" group="lower-Greek" /> 他们的工作解决了 19 世纪神经解剖学中长期存在的争议；高尔基自己则坚持神经系统的网络模型。

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19 世纪的科学家研究了电信号在整个神经（nerves）（即神经元束）中的传播，并证明神经组织是由细胞组成的，而不是一个互相连接的管网（''reticulum''）。Carlo Matteucci 继续 Galvani 的研究，证明细胞膜上存在电压，可以产生直流电。受 Carlo Matteucci 的工作启发，德国生理学家 [[Emil du Bois-Reymond]] 在1843 年发现了动作电位。<ref name=":21" /> 动作电位的传导速率最早是在 1850 年由 Hermann von Helmholtz 测量的。<ref name=":22" /> 为了证明神经组织是由独立的细胞组成的，西班牙物理学家 [[Santiago Ramón y Cajal]] 和他的学生们使用 Camillo Golgi 开发的染色剂揭示了大量的神经元形状，他们煞费苦心地进行了绘制。由于他们的发现，Golgi 和 [[Santiago Ramón y Cajal|Ramón y Cajal]] 获得了 1906 年的诺贝尔生理学奖。<ref name="Nobel_1906" group="lower-Greek" /> 他们的工作解决了 19 世纪神经解剖学中长期存在的争议；高尔基自己则坚持神经系统的网络模型。

[[Image:3b8e.png|thumb|right|钠钾泵在 E2-Pi 状态下的带状图（Ribbon diagram）。推测的脂双层边界显示为蓝色（胞内）和红色（胞外）的面。|链接=Special:FilePath/3b8e.png]]

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The 20th century was a significant era for electrophysiology. In 1902 and again in 1912, [[Julius Bernstein]] advanced the hypothesis that the action potential resulted from a change in the [[permeation|permeability]] of the axonal membrane to ions.<ref name="bernstein_1902_1912" group="lower-alpha">{{cite journal | vauthors = Bernstein J | year = 1902 | title = Untersuchungen zur Thermodynamik der bioelektrischen Ströme | journal = Pflügers Archiv für die gesamte Physiologie | volume = 92 | pages = 521–562 | doi = 10.1007/BF01790181 | issue = 10–12| s2cid = 33229139 | author-link = Julius Bernstein | url = https://zenodo.org/record/2192363 }}</ref>{{sfn|Bernstein|1912}} Bernstein's hypothesis was confirmed by [[Kenneth Stewart Cole|Ken Cole]] and Howard Curtis, who showed that membrane conductance increases during an action potential.<ref group="lower-alpha" name=":16">{{cite journal | vauthors = Cole KS, Curtis HJ | title = Electric Impedance of the Squid Giant Axon During Activity | journal = The Journal of General Physiology | volume = 22 | issue = 5 | pages = 649–70 | date = May 1939 | pmid = 19873125 | pmc = 2142006 | doi = 10.1085/jgp.22.5.649 | author-link1 = Kenneth Stewart Cole }}</ref> In 1907, [[Louis Lapicque]] suggested that the action potential was generated as a threshold was crossed,<ref group="lower-alpha" name=":17">{{cite journal | vauthors = Lapicque L | year = 1907 | title = Recherches quantitatives sur l'excitationelectrique des nerfs traitee comme une polarisation | journal = J. Physiol. Pathol. Gen | volume = 9| pages = 620–635 }}</ref> what would be later shown as a product of the [[dynamical system]]s of ionic conductances. In 1949, [[Alan Lloyd Hodgkin|Alan Hodgkin]] and [[Bernard Katz]] refined Bernstein's hypothesis by considering that the axonal membrane might have different permeabilities to different ions; in particular, they demonstrated the crucial role of the sodium permeability for the action potential.<ref name="hodgkin_1949" group="lower-alpha">{{cite journal | vauthors = Hodgkin AL, Katz B | title = The effect of sodium ions on the electrical activity of giant axon of the squid | journal = The Journal of Physiology | volume = 108 | issue = 1 | pages = 37–77 | date = March 1949 | pmid = 18128147 | pmc = 1392331 | doi = 10.1113/jphysiol.1949.sp004310 | author-link1 = Alan Lloyd Hodgkin | author-link2 = Bernard Katz }}</ref> They made the first actual recording of the electrical changes across the neuronal membrane that mediate the action potential.<ref group="lower-Greek" name=":0">{{cite journal |last=Warlow|first=Charles| name-list-style = vanc |title=The Recent Evolution of a Symbiotic Ion Channel in the Legume Family Altered Ion Conductance and Improved Functionality in Calcium Signaling|journal=Practical Neurology|volume=7|issue=3|pages=192–197|url=http://pn.bmj.com/content/7/3/192.full|publisher=BMJ Publishing Group|access-date=23 March 2013|url-status=live|archive-url=https://web.archive.org/web/20120314104408/http://pn.bmj.com/content/7/3/192.full|archive-date=14 March 2012|df=dmy-all|date=June 2007}}</ref> This line of research culminated in the five 1952 papers of Hodgkin, Katz and [[Andrew Huxley]], in which they applied the [[voltage clamp]] technique to determine the dependence of the axonal membrane's permeabilities to sodium and potassium ions on voltage and time, from which they were able to reconstruct the action potential quantitatively.<ref name="hodgkin_1952" group="lower-alpha" /> Hodgkin and Huxley correlated the properties of their mathematical model with discrete [[ion channel]]s that could exist in several different states, including "open", "closed", and "inactivated". Their hypotheses were confirmed in the mid-1970s and 1980s by [[Erwin Neher]] and [[Bert Sakmann]], who developed the technique of [[patch clamp]]ing to examine the conductance states of individual ion channels.<ref name="patch_clamp" group="lower-alpha">{{cite journal | vauthors = Neher E, Sakmann B | title = Single-channel currents recorded from membrane of denervated frog muscle fibres | journal = Nature | volume = 260 | issue = 5554 | pages = 799–802 | date = April 1976 | pmid = 1083489 | doi = 10.1038/260799a0 | author-link1 = Erwin Neher | bibcode = 1976Natur.260..799N | s2cid = 4204985 }} * {{cite journal | vauthors = Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ | title = Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches | journal = Pflügers Archiv | volume = 391 | issue = 2 | pages = 85–100 | date = August 1981 | pmid = 6270629 | doi = 10.1007/BF00656997 | s2cid = 12014433 }} * {{cite journal | vauthors = Neher E, Sakmann B | title = The patch clamp technique | journal = Scientific American | volume = 266 | issue = 3 | pages = 44–51 | date = March 1992 | pmid = 1374932 | doi = 10.1038/scientificamerican0392-44 | author-link1 = Erwin Neher | bibcode = 1992SciAm.266c..44N }}</ref> In the 21st century, researchers are beginning to understand the structural basis for these conductance states and for the selectivity of channels for their species of ion,<ref name="yellen_2002" group="lower-alpha">{{cite journal | vauthors = Yellen G | title = The voltage-gated potassium channels and their relatives | journal = Nature | volume = 419 | issue = 6902 | pages = 35–42 | date = September 2002 | pmid = 12214225 | doi = 10.1038/nature00978 | bibcode = 2002Natur.419...35Y | s2cid = 4420877 }}</ref> through the atomic-resolution [[X-ray crystallography|crystal structures]],<ref name="doyle_1998" group="lower-alpha">{{cite journal | vauthors = Doyle DA, Morais Cabral J, Pfuetzner RA, Kuo A, Gulbis JM, Cohen SL, Chait BT, MacKinnon R | display-authors = 6 | title = The structure of the potassium channel: molecular basis of K+ conduction and selectivity | journal = Science | volume = 280 | issue = 5360 | pages = 69–77 | date = April 1998 | pmid = 9525859 | doi = 10.1126/science.280.5360.69 | bibcode = 1998Sci...280...69D }} * {{cite journal | vauthors = Zhou Y, Morais-Cabral JH, Kaufman A, MacKinnon R | title = Chemistry of ion coordination and hydration revealed by a K+ channel-Fab complex at 2.0 A resolution | journal = Nature | volume = 414 | issue = 6859 | pages = 43–8 | date = November 2001 | pmid = 11689936 | doi = 10.1038/35102009 | bibcode = 2001Natur.414...43Z | s2cid = 205022645 }} * {{cite journal | vauthors = Jiang Y, Lee A, Chen J, Ruta V, Cadene M, Chait BT, MacKinnon R | title = X-ray structure of a voltage-dependent K+ channel | journal = Nature | volume = 423 | issue = 6935 | pages = 33–41 | date = May 2003 | pmid = 12721618 | doi = 10.1038/nature01580 | bibcode = 2003Natur.423...33J | s2cid = 4347957 }}</ref> fluorescence distance measurements<ref name="FRET" group="lower-alpha">{{cite journal | vauthors = Cha A, Snyder GE, Selvin PR, Bezanilla F | title = Atomic scale movement of the voltage-sensing region in a potassium channel measured via spectroscopy | journal = Nature | volume = 402 | issue = 6763 | pages = 809–13 | date = December 1999 | pmid = 10617201 | doi = 10.1038/45552 | bibcode = 1999Natur.402..809C | s2cid = 4353978 }} * {{cite journal | vauthors = Glauner KS, Mannuzzu LM, Gandhi CS, Isacoff EY | title = Spectroscopic mapping of voltage sensor movement in the Shaker potassium channel | journal = Nature | volume = 402 | issue = 6763 | pages = 813–7 | date = December 1999 | pmid = 10617202 | doi = 10.1038/45561 | bibcode = 1999Natur.402..813G | s2cid = 4417476 }} * {{cite journal | vauthors = Bezanilla F | title = The voltage sensor in voltage-dependent ion channels | journal = Physiological Reviews | volume = 80 | issue = 2 | pages = 555–92 | date = April 2000 | pmid = 10747201 | doi = 10.1152/physrev.2000.80.2.555 }}</ref> and [[cryo-electron microscopy]] studies.<ref name="cryoEM" group="lower-alpha">{{cite journal | vauthors = Catterall WA | title = A 3D view of sodium channels | journal = Nature | volume = 409 | issue = 6823 | pages = 988–9, 991 | date = February 2001 | pmid = 11234048 | doi = 10.1038/35059188 | bibcode = 2001Natur.409..988C | s2cid = 4371677 | doi-access = free }} * {{cite journal | vauthors = Sato C, Ueno Y, Asai K, Takahashi K, Sato M, Engel A, Fujiyoshi Y | title = The voltage-sensitive sodium channel is a bell-shaped molecule with several cavities | journal = Nature | volume = 409 | issue = 6823 | pages = 1047–51 | date = February 2001 | pmid = 11234014 | doi = 10.1038/35059098 | bibcode = 2001Natur.409.1047S | s2cid = 4430165 }}</ref>

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20 ~~世纪是电生理的重要时期。1902 年和~~ 1912 ~~年，Julius Bernstein 提出了动作电位是由轴突膜对离子的渗透性改变引起的假说。~~<ref name="bernstein_1902_1912" group="lower-alpha" /> Ken Cole 和 Howard Curtis 证实了 Bernstein 的假说，他们发现在动作电位期间膜电导增加。<ref name=":16" group="lower-alpha" /> 1907年，Louis Lapicque ~~提出，动作电位产生的阈值被跨越,~~<ref name=":17" group="lower-alpha" /> ~~w，后来被证明为离子电导动力学系统的乘积。1949年，Alan~~ Hodgkin 和 Bernard Katz 完善了 Bernstein 的假说，他们认为轴突膜对不同的离子可能有不同的通透性；特别是，他们证明了钠通透性对动作电位的关键作用。<ref name="hodgkin_1949" group="lower-alpha" /> 。他们首次实际记录了神经元膜上的电变化，这些电变化介导了动作电位。<ref name=":0" group="lower-Greek" /> 这一系列的研究在 Hodgkin，Katz 和 Andrew Huxley 的 5 篇 1952 年的论文中达到了顶峰，他们应用电压钳技术来确定轴突膜对钠离子和钾离子的通透性对电压和时间的依赖性，从而能够定量地重建动作电位。<ref name="hodgkin_1952" group="lower-alpha" /> 。Hodgkin 和 Huxley 将其数学模型的性质与离散离子通道相关联，离散离子通道可以存在于几种不同的状态，包括“开放”、“封闭”和“失活”。他们的假设在20世纪70年代中期和80年代得到 Erwin Neher 和 Bert Sakmann 的证实，他们发明了膜片钳技术来检测单个离子通道的电导状态。<ref name="patch_clamp" group="lower-alpha" /> 。在21世纪，通过原子分辨率晶体结构，<ref name="doyle_1998" group="lower-alpha" /> 研究人员开始了解这些电导态的结构基础，以及离子种类的通道选择性，<ref name="yellen_2002" group="lower-alpha" /> 荧光距离测量<ref name="FRET" group="lower-alpha" /> 和冷冻电子显微研究。<ref name="cryoEM" group="lower-alpha" />

+

20 世纪是电生理的重要时期。Julius Bernstein 于 1902 和 1912 两次提出动作电位是由轴突膜对离子的渗透性的改变引起的假说。<ref name="bernstein_1902_1912" group="lower-alpha" /> Ken Cole 和 Howard Curtis 证实了 Bernstein 的假说，他们发现在动作电位期间膜电导增加。<ref name=":16" group="lower-alpha" /> 1907年，Louis Lapicque 提出，动作电位因膜电位跨过阈值而产生，<ref name=":17" group="lower-alpha" /> 后来被证明为离子电导的动力学系统的结果。1949年，Alan Hodgkin 和 Bernard Katz 完善了 Bernstein 的假说，他们认为轴突膜对不同的离子可能有不同的通透性；特别是，他们证明了钠通透性对动作电位的关键作用。<ref name="hodgkin_1949" group="lower-alpha" /> 。他们首次实际记录了神经元膜上的电变化，这些电变化介导了动作电位。<ref name=":0" group="lower-Greek" /> 这一系列的研究在 Hodgkin，Katz 和 Andrew Huxley 的 5 篇 1952 年的论文中达到了顶峰，他们应用电压钳技术来确定轴突膜对钠离子和钾离子的通透性对电压和时间的依赖性，从而能够定量地重建动作电位。<ref name="hodgkin_1952" group="lower-alpha" /> 。Hodgkin 和 Huxley 将其数学模型的性质与离散离子通道相关联，离散离子通道可以存在于几种不同的状态，包括“开放”、“封闭”和“失活”。他们的假设在20世纪70年代中期和80年代得到 Erwin Neher 和 Bert Sakmann 的证实，他们发明了膜片钳技术来检测单个离子通道的电导状态。<ref name="patch_clamp" group="lower-alpha" /> 。在21世纪，通过原子分辨率晶体结构，<ref name="doyle_1998" group="lower-alpha" /> 研究人员开始了解这些电导态的结构基础，以及离子种类的通道选择性，<ref name="yellen_2002" group="lower-alpha" /> 荧光距离测量<ref name="FRET" group="lower-alpha" /> 和冷冻电子显微研究。<ref name="cryoEM" group="lower-alpha" />

也是 Julius Bernstein 首次将能斯特方程（[[Nernst equation]] ）引入描述跨膜静息电位；David E. Goldman 在 1943 年将这个方程推广到了以他的名字命名的戈德曼方程（[[Goldman equation]]）。<ref name="goldman_1943" group="lower-alpha" /> 钠钾泵在 1957 年被鉴定出来 <ref name=":18" group="lower-alpha">{{cite journal | vauthors = Skou JC | title = The influence of some cations on an adenosine triphosphatase from peripheral nerves | journal = Biochimica et Biophysica Acta | volume = 23 | issue = 2 | pages = 394–401 | date = February 1957 | pmid = 13412736 | doi = 10.1016/0006-3002(57)90343-8 }}</ref><ref name=":1" group="lower-Greek">{{cite press release | url = http://nobelprize.org/nobel_prizes/medicine/laureates/1997/press.html | title = The Nobel Prize in Chemistry 1997 | publisher = The Royal Swedish Academy of Science | year = 1997 | access-date = 2010-02-21 | url-status = live | archive-url = https://web.archive.org/web/20091023003257/http://nobelprize.org/nobel_prizes/medicine/laureates/1997/press.html | archive-date = 23 October 2009 | df = dmy-all }}</ref>，其性质逐渐被阐明，<ref name="hodgkin_1955" group="lower-alpha">{{cite journal | vauthors = Hodgkin AL, Keynes RD | title = Active transport of cations in giant axons from Sepia and Loligo | journal = The Journal of Physiology | volume = 128 | issue = 1 | pages = 28–60 | date = April 1955 | pmid = 14368574 | pmc = 1365754 | doi = 10.1113/jphysiol.1955.sp005290 | author-link1 = Alan Lloyd Hodgkin }}</ref><ref name="caldwell_1960" group="lower-alpha">{{cite journal | vauthors = Caldwell PC, Hodgkin AL, Keynes RD, Shaw TL | title = The effects of injecting 'energy-rich' phosphate compounds on the active transport of ions in the giant axons of Loligo | journal = The Journal of Physiology | volume = 152 | issue = 3 | pages = 561–90 | date = July 1960 | pmid = 13806926 | pmc = 1363339 | doi = 10.1113/jphysiol.1960.sp006509 }}</ref><ref name="caldwell_1957" group="lower-alpha">{{cite journal | vauthors = Caldwell PC, Keynes RD | title = The utilization of phosphate bond energy for sodium extrusion from giant axons | journal = The Journal of Physiology | volume = 137 | issue = 1 | pages = 12–3P | date = June 1957 | pmid = 13439598 | doi = 10.1113/jphysiol.1957.sp005830 | s2cid = 222188054 }}</ref> 最终用 X 射线晶体学（[[X-ray crystallography]]）测定其原子分辨率的结构。<ref name="Na_K_pump_structure" group="lower-alpha">{{cite journal | vauthors = Morth JP, Pedersen BP, Toustrup-Jensen MS, Sørensen TL, Petersen J, Andersen JP, Vilsen B, Nissen P | display-authors = 6 | title = Crystal structure of the sodium-potassium pump | journal = Nature | volume = 450 | issue = 7172 | pages = 1043–9 | date = December 2007 | pmid = 18075585 | doi = 10.1038/nature06419 | bibcode = 2007Natur.450.1043M | s2cid = 4344526 }}</ref> 相关的离子泵的晶体结构也已经被解析，为理解这些分子机器的工作原理提供了更广阔的图景。<ref name=":19" group="lower-alpha">{{cite journal | vauthors = Lee AG, East JM | title = What the structure of a calcium pump tells us about its mechanism | journal = The Biochemical Journal | volume = 356 | issue = Pt 3 | pages = 665–83 | date = June 2001 | pmid = 11389676 | pmc = 1221895 | doi = 10.1042/0264-6021:3560665 }}</ref>

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