Related Experiment Video
Updated: Aug 8, 2026

Measurement of Extracellular Ion Fluxes Using the Ion-selective Self-referencing Microelectrode Technique
Published on: May 3, 2015
Electrochemical gradients and k and cl fluxes in excised corn roots
1Department of Botany, Rutgers University, Newark, New Jersey 07102.
Abstract:
The compartmental analysis method was used to estimate the K(+) and Cl(-) fluxes for cells of excised roots of Zea mays L. cv. Golden Bantam. When the measured fluxes are compared to those calculated with the Ussing-Teorell flux-ratio equation, an active inward transport of Cl(-) across the plasmalemma is indicated; the plasmalemma K(+) fluxes are not far different from those predicted for passive diffusion, although an active inward transport cannot be precluded. Whether fluxes across the tonoplast are active or passive depends upon the vacuolar potential which is unknown. Assuming no electropotential gradient, the tracer flux ratios are fairly close to those predicted for passive movement. However, if the vacuole is positive by about 10 millivolts relative to the cytoplasm, the data suggest active inward transport for K(+) and outward transport for Cl(-).Fluxes to the xylem exudate were found to be more accurately estimated from the specific radioactivity of the cytoplasm (symplasm) than from the external solution specific radioactivity. The electrochemical gradients for K(+) and Cl(-) between the xylem vessels and the surrounding stelar parenchyma indicate active K(+) and passive Cl(-) movement into the vessels. The data are interpreted as being in accord with radial transport through the symplast into living vessels.
More Related Videos
05:42Measurement of Ion Concentration in the Unstirred Boundary Layer with Open Patch-Clamp Pipette: Implications in Control of Ion Channels by Fluid Flow
Published on: January 7, 2019
10:08Study of the Functions and Activities of Neuronal K-Cl Co-Transporter KCC2 Using Western Blotting
Published on: December 9, 2022
Related Concept Videos
Electrochemical Gradient and Channel Proteins: An Overview
The electrical gradient: The electrical gradient across cell membranes refers to the difference in electric charge between the inside and outside of a cell. This difference drives the movement of ions towards or away from the cells. For instance, if the inside of the cell is more negatively charged relative to the...
What is an Electrochemical Gradient?
Ion Channels
Ion channels are specialized integral membrane proteins on the plasma membrane that allow specific...
Processes at Electrodes
Resting Potential Decay
At rest, the K+ is the main ion that moves across the membrane through...
Water and Mineral Acquisition