MECHANICAL, THERMAL, AND OPTICAL SIGNS OF EXCITATION IN THE NERVOUS SYSTEM

在本财政年度的初期，我们集中力量， 检测和分析水陆两用车中的热和机械变化 由交感神经刺激产生的皮肤腺体。 我们制作 热传感器设计成与所研究的皮肤区域相匹配， 成功地记录了与去甲肾上腺素释放相关的热量， 神经末梢 我们发现这种热量的出现早于 交感神经的机械和电反应开始 刺激在研究动物的行为中具有特殊的意义。 去甲肾上腺素作用于皮肤腺体 在这次会议上举行的物理化学家和化学工程师会议上， 1989年12月10日，一个有趣的信息是， 报道 具有负固定电荷的聚合物凝胶被证明经历 相变伴随可逆的、不连续的体积变化。 因为我们在寻找一个坚实的物理化学基础来解释 神经组织中快速机械变化的本质，我们开始了一个 研究合成聚合物凝胶中的溶胀现象。 我们 发现聚（丙烯酸）凝胶浸入盐溶液中， 单价阳离子（例如，钠或钾）和二价阳离子 (e.g.,钙）以两种稳定状态之一存在，要么膨胀， 压缩（收缩）。 我们还测量了与这些相关的产热， 不连续的音量转换。 我们现在认为， 在神经的浅层发生不连续的过渡 细胞和纤维，这些过渡对应于开始， 动作电位的终点。

During the early part of this fiscal year, we concentrated our effort in detecting and analyzing thermal and mechanical changes in the amphibian dermal glands produced by sympathetic nerve stimulation. We fabricated heat sensors designed to match the area of the skin under study and succeeded in recording the heat associated with noradrenaline release from the nerve terminals. Our finding that the onset of this heat precedes the beginning of the mechanical and electrical responses to sympathetic nerve stimulation is of special significance in the study of the action of noradrenaline on the dermal glands. In a meeting of physical chemists and chemical engineers held at this campus on December 10, 1989, an interesting piece of information was reported. Polymer gels with negative fixed charges were shown to undergo phase transitions accompanying reversible, discontinuous volume changes. Since we were in search of a solid physicochemical basis for explaining the nature of the rapid mechanical changes in nervous tissues, we began an investigation of the phenomenon of swelling in synthetic polymer gels. We found that poly (acrylic acid) gels immersed in salt solutions containing both univalent cations (e.g., sodium or potassium) and divalent cations (e.g., calcium) exist in one of the two stable states, either swollen or compact (shrunk). We also measured heat production associated with these discontinuous volume transitions. We now believe that similar discontinuous transitions take place in the superficial layer of nerve cells and fibers and that these transitions correspond to the beginning and end of an action potential.