抄録
1. In Ringer's solution in which Na was replaced with Tris-(hydroxymethyl)-aminomethane (abbreviated as Tris), the electrical properties of the sartorius muscle fiber of a frog (Rana nigromaculata nigromaculata) was investigated.
2. In Tris-Cl Ringer's solution, the effective membrane resistance was decreased at the depolarization and increased at the hyperpolarization, while in Tris-SO4 Ringer's solution it was increased at the depolarization and decreased at the hyperpolarization. It might be due to the change of the Cl conductance at the strong polarization. The Cl conductance was also changed with time and it seemed to be one of the reasons to produce the delayed rectification.
3. In Tris-SO4 Ringer's solution, the same graded slow response as that in Cl-free solution with normal Na concentration was observed after termination of the strong anodal pulse. Na is not considered to have an essential effect on the response in Cl-free solution. The same result was also obtained in K-rich solution. The slow break response appeared as a negative potential component in low K solution, while it did as a positive potential component in K-rich solution. In the former, the effective membrane resistance was decreased during the production of the response, while in the latter it was increased. It might be explained mainly by the change of the K conductance.
