The effect of multivalent cations on the membrane potential of the ehrlich ascites tumor cell

✍ Scribed by Thomas C. Smith; Terry M. Mikiten; Charles Levinson

• Publisher: John Wiley and Sons
• Year: 1972
• Tongue: English
• Weight: 672 KB
• Volume: 79
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1040790114

✦ Synopsis

The effect of di-and trivalent cations on the membrane potential of the Ehrlich ascites tumor cell has been investigated using micro-electrode techniques. In solutions free of multivalent cations the average membrane potential for 46 cells was 8.3 f 0.5 mv (SE). However, the potentials were not stable and decayed with a half-time of about six seconds. Addition of Ca++ decreased the rate of decay and concomitantly increased the membrane potential. The magnitude of these effects was a function of the Ca++ concentration. At the optimum concentration (2 mM), the half-time of decay was increased to 12 seconds and the membrane potential was raised to 17.8 f 1.7 mv (SE). The related alkaline-earth cations, Sr++, Ba++ and Mg++ had similar effects on both the stability and magnitude of the membrane potential. The effect of La+++, which was qualitatively similar to that of the divalent cations, was also concentration dependent. However, 100-fold lower concentrations were adequate to achieve comparable effects. Moreover, membrane potentials were stable for up to ten minutes in La+++-containing solutions. Variations in intracellular C1content induced by temperature changes were paralleled by changes in membrane potentials. However, the potentials were not those expected for a simple C1-electrode.