Bernsteins Hypothesis for the Resting Potential

In 1902, Julius Bernstein proposed the first satisfactory hypothesis for generation of the resting potential. Bernstein knew that the inside of cells have high K+ and low Na+ concentrations and that the extracellular fluid has low K+ and high Na+ concentrations. In addition, there appeared to be large negatively charged molecules, presumably proteins, to which the cell was impermeable. Bernstein also knew (a critical piece of information) that cells were highly permeable to K+ but not very permeable to other ions. Furthermore, Bernstein knew of the work of the physical chemist, Nernst. Bernstein therefore suggested that the resting potential could be predicted simply by applying the Nernst equilibrium equation for potassium:

Bernstein Hypothesis

Potassium Concentration (mM)

FIGURE 4 Effects of altered extracellular concentrations of K+ on the membrane potential: (•), measured membrane potential at each of a variety of different concentrations of K+; the straight line is the potential predicted by the Nernst equation. The value of 140 in the Nernst equation is the estimated intracellular concentration of K+ for the cell used in the experiment. (Modified from Hodgkin AL, Horowicz P. J Physiol 1959; 148:127.)

Potassium Concentration (mM)

FIGURE 4 Effects of altered extracellular concentrations of K+ on the membrane potential: (•), measured membrane potential at each of a variety of different concentrations of K+; the straight line is the potential predicted by the Nernst equation. The value of 140 in the Nernst equation is the estimated intracellular concentration of K+ for the cell used in the experiment. (Modified from Hodgkin AL, Horowicz P. J Physiol 1959; 148:127.)

where Vm is the membrane potential and EK the potassium equilibrium potential (see also Chapter 3).

Although Bernstein's hypothesis was interesting, it could not be directly tested at the time (hence, the question mark in the equation) because microelectrode recording techniques had not been developed. It was not until the 1930s and 1940s and the advent of microelec-trode recording techniques that it became possible to test the hypothesis directly. The testing of Bernstein's hypothesis was done primarily by Hodgkin and Huxley and their colleagues in England. As a result of this work, a general theory was developed for the generation of the resting potential that appears to be applicable to most cells in the body.

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Responses

  • luwam simon
    What is bernstein's hypothesis?
    7 years ago

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