Related Experiment Video
Updated: Jun 19, 2026

Measuring Fluxes of Mineral Nutrients and Toxicants in Plants with Radioactive Tracers
Published on: August 22, 2014
PROTOPLASMIC POTENTIALS IN HALICYSTIS : II. THE EFFECTS OF POTASSIUM ON TWO SPECIES WITH DIFFERENT SAPS
1Laboratories of The Rockefeller Institute for Medical Research.
Abstract:
The potential difference across the protoplasm of impaled cells of two American species of Halicystis is compared. The mean value for H. Osterhoutii is 68.4 mv.; that for H. ovalis is 79.7 mv., the sea water being positive to the sap in both. The higher potential of H. ovalis is apparently due to the higher concentration of KCl (0.3 M) in its vacuolar sap. When the KCl content of H. Osterhoutii sap (normally 0.01 M or less) is experimentally raised to 0.3 M, the potential rises to values about equal to those in H. ovalis. The external application of solutions high in potassium temporarily lowers the potential of both, probably by the high mobility of K(+) ions. But a large potential is soon regained, representing the characteristic potential of the protoplasm. This is about 20 mv. lower than in sea water. The accumulation of KCl in the sap of H. ovalis is apparently not due to the higher mobility of K(+) ion in its protoplasm, since the electrical effects of potassium are practically identical in H. Osterhoutii, where KCl is not accumulated.
More Related Videos
08:11Voltage-Dependent Potassium Current Recording on H9c2 Cardiomyocytes via the Whole-Cell Patch-Clamp Technique
Published on: November 11, 2022
16:16Membrane Potentials, Synaptic Responses, Neuronal Circuitry, Neuromodulation and Muscle Histology Using the Crayfish: Student Laboratory Exercises
Published on: January 18, 2011
Related Concept Videos
Responses to Salt Stress
ATP Driven Pumps I: An Overview
There are four main types of ATP-driven pumps - P-type, V-type, F-type, and ABC transporter. All these pumps are of varying complexities and are...
Resting Potential Decay
At rest, the K+ is the main ion that moves across the membrane through...
The Resting Membrane Potential
Tonicity in Plants
Tonicity in Plants
Tonicity
Tonicity describes the capacity of a cell to lose or gain water depending on the solute...