Tasaki I
LCB, National Institute of Mental Health, Bethesda, MD 20892.
Physiol Chem Phys Med NMR. 1988;20(4):251-68.
(1) Nerve fibers and cells were shown to swell when they develop action potentials. Both in the squid giant axon and in the garfish olfactory nerve, the peak of swelling coincides with the peak of the action potential recorded from the site of mechanical recording. Substitution of univalent cations for the bivalent cations (Ca) bound to multi-anion sites in the membrane macromolecules is considered to be at the base of the phenomenon of swelling. (2) Measurements of heat production by the garfish olfactory nerve indicate that the rate of temperature rise is maximal at the peak of the action potential. Since heat production lasts for the entire depolarizing phase of the action potential, the "condenser theory" of heat production is abandoned. Again, substitution of the bound bivalent cations in the membrane macromolecules with univalent cations is regarded as the origin of nerve heat. (3) The two stable states of the nerve membrane, which are readily demonstrable in TEA-treated or internally perfused squid giant axons, are shown to represent bivalent cation-rich and univalent cation-rich states of the nerve membrane. (4) A physicochemical theory is described that explains macromolecular transitions between two stable states. The mechanism of nerve excitation is explained on a physicochemical basis. (5) The importance of the role played by water molecules in the process of nerve excitation is emphasized.
(1) 当神经纤维和细胞产生动作电位时，它们会肿胀。在乌贼巨大轴突和雀鳝嗅神经中，肿胀的峰值与机械记录部位记录到的动作电位峰值一致。膜大分子中与多阴离子位点结合的二价阳离子（Ca）被单价阳离子取代被认为是肿胀现象的基础。(2) 对雀鳝嗅神经产热的测量表明，温度上升速率在动作电位峰值时最大。由于产热持续整个动作电位的去极化阶段，因此放弃了产热的“电容器理论”。同样，膜大分子中结合的二价阳离子被单价阳离子取代被视为神经产热的起源。(3) 在经TEA处理或内部灌注的乌贼巨大轴突中很容易证明的神经膜的两种稳定状态，被证明分别代表神经膜富含二价阳离子和富含单价阳离子的状态。(4) 描述了一种物理化学理论，该理论解释了两种稳定状态之间的大分子转变。从物理化学角度解释了神经兴奋的机制。(5) 强调了水分子在神经兴奋过程中所起作用的重要性。
