The membrane potential of Ehrlich ascites tumor cells microelectrode measurements and their critical evaluation

Abstract

Intracellular potentials were measured, using a piezoelectric electromechanical transducer to impale Ehrlich ascites tumor cells with capillary microelectrodes. In sodium Ringer's, the potential immediately after the penetration was -24±7 mV, and decayed to a stable value of about -8 mV within a few msec. The peak potentials disappeared in potassium Ringer's and reappeared immediately after resuspension in sodium. Ringer's, whereas the stable potentials were only slightly influenced by the change of medium. The peak potential is in good agreement with the Nernst potential for chloride. This is also the case when cell sodium and potassium have been changed by addition of ouabain. It is concluded that the peak potentials represent the membrane potential of the unperturbed cell, and that chloride is in electrochemical equilibrium across the cell membrane.The membrane potential of about -11 mV previously reported corresponds to the stable potential in this study, and is considered as a junction potential between damaged cells and their environment. Similar potential differences were recorded between a homogenate of cells and Ringer's.The apparent membrane resistance of Ehrlich cells was about 70 Ωcm(2). This is two orders of magnitude less than the value calculated from(36)Cl fluxes, and may, in part, represent a leak in the cell membrane.For comparison, the influence of an eventual leak on measurements in red cells and mitochondria is discussed.

Membrane potential, chloride exchange, and chloride conductance in Ehrlich mouse ascites tumour cells.

“…(Hendil & Hoffmann, 1974), a dry to wet weight ratio of 0-24, and that a single cell has a volume of 1-93 x 10-ml. and a surface area of 1-0 x 10-5 cm' (Lassen, Nielsen, Pape & Simonsen, 1971)). …”

Oscillatory hyperpolarizations and resting membrane potentials of mouse fibroblast and macrophage cell lines.

“…None the less, properties of L cells, such as phagocytosis (Okada, Tsuchiya, Yada, Yano & Yawo, 1981), cell motility (Tsuchiya, Okada, Yano, Inouye, Saski & Doida, 1981 a), and pinocytosis (Tsuchiya, Okada, Yano, Murai, Miyahara & Tanaka, 1981 b) have been associated with such hyperpolarizations, and in macrophages these hyperpolarizations have been associated with chemotaxis (Gallin & Gallin, 1977) and phagocytosis (Kouri, Noa, Diaz & Niubo, 1980). Recently, we analysed the fast potential transient seen after impalement (Lassen, Nielson, Pape & Simonsen, 1971) into macrophages and found (Ince, Ypey, Van Furth & Verveen, 1983b) that penetratation by a microelectrode induces a leakage conductance across the membrane and that the membrane potentials of macrophages (mean -40 mV) are two to three times more negative than has generally been thought on the basis of sustained potential measurements (-15 to -25 mV). In the present study we measured fast potential transients upon impalement in L cells and macrophages in order to determine the origin of spontaneous hyperpolarizations and to assess the effect of the leakage conductance induced by the micro-electrode on membrane potential measurements.…”

Mitochondrial Membrane Potential: Evidence from Studies with a Fluorescent Probe

“…They proposed that a similar perhaps faster decay took place in our experiments. However, in at least some other studies [e.g., Sekiya's (8) (14) and [4][5][6][7][8][9][10][11][12][13] 1cm2 (15) have been recorded from the excitable face and 0.1-0.4 flCm2 (15) for the nonexcitable face.A number of studies have attempted to estimate the mitochondrial membrane potential by indirect means. Harris and Pressman (5) have calculated membrane potentials in rat liver mitochondria from anion distributions.…”

“…Lassen et al (7) found in Ehrlich ascites tumor cells using a similar microelectrode system, a membrane potential which depended on the K+ concentration of the medium and which decayed in a few milliseconds. After the initial decay, the steady-state potential was no longer affected by the K+ in the medium.…”

“…However, in at least some other studies [e.g., Sekiya's (8) and Johnstone's (9) ] the K+-sensitive membrane potential decayed considerably more slowly (with a half-time of 10 sec in Sekiya's work). Consequently, the results of Lassen (14) and [4][5][6][7][8][9][10][11][12][13] 1cm2 (15) (14). Several other workers estimate much larger potentials in actively metabolizing mitochondria.…”