抄録
1) Effects of alkali metal and alkaline earth metal ions upon the slopefactor and the intensity-factor in electric excitation of nerve were investigated. Fabre's “constante linéaire” (c. l.) was measured by an improved method. The ions studied were K, NH4, Na, Ca and Mg. The isotonic solutions of their chloride were mixed with Ringer solution at various proportions, and changes in the c. l. and the rheobase V after the application were traced.
2) All the ions of the two groups, alkali metal and alkaline earth metalions, affect the c. l. of the nerve in substantially the same manner. At low concentrations they increase the c. L and at high they decrease it, and there exists a certain intermediate concentration, at which there is practically no change in the c. l. These two opposite effects are however, at every concentration, manifestations of the two different phases in the effect of the ions, namely the c. l.decreasing effect in the early phase and the c. l.-increasing effect in the later phase.
3) Between the alkali metal and alkaline earth metal ions there is a remarkable quantitative difference in the value of the intermediate concentration and in the relative intensities of the two different phases stated above. One may therefore speak of a quantitative antagonism between them.
4) The changes in the rheobase V and the threshold strength I for the saturation current run parallel with that in the c. l; they change their magnitudes in the same direction, the change in I being always more pronounced than that in V. This change in I (proportional to the “pente limite, ” i. e. the direct expression of the slope-factor) and in V (the intensity-factor) is a typical one brought about by the variation of environmental conditions of excitable tissues.
