Abstract
The membrane potential of Ehrlich ascites tumor cell was determined with the use of a microelectrode under direct microscopic observation. Further, examinations were made on the effect of certain physical factors in environment upon the membrane potentials. The results thereby obtained are summarized as follows:
1) On the impalement of microelectrode into the cell, both positive and negative potentials were obtained.
2) The negative potential observed was invariably unstable and its time-course was characterized by a rather slow rise to the muximum and a gradual decay to a zero potential level, after staying in the maximum magnitude for only a very short duration. The mean maximum value of the potentials was -16.9±0.5mV.
The potential decreased markedly in the course of time after aspiration of the tumor cell.
The potential decreased significantly as the external hydrogen ion concentration increased.
The potential showed no significant change with the change of temperature within the range from 16°C to 37°C. However, it has a very small but positive temperature coefficient.
The increase of external potassium concentration caused the decrease of potential. Nearly a linear relationship could be found with the potential change on log [K]0 of more than 32.0meq/L. The change in potential with a tenfold change in external potassium concentration was only 19.2mV.
3) The positive potential showed an intimate correlation with the tip junction potential of the microelectrode.
