Why The Reversal Potential For Potassium Determines The Resting Membrane Potential Of A Given Cell

1327 Words Oct 30th, 2016 6 Pages
In order to determine the extent to which the reversal potential for potassium determines the resting membrane potential of a given cell, a mechanism is needed to determine the change in membrane voltage across the cell in different extracellular potassium solutions. The intracellular recording technique consists of puncturing a prepared cell with a conductive pipette. The difference in potential between the extracellular electrode and the wire in the pipette is recorded and displayed on the voltage vs. time graph. Figure 1 provides an example of an intracellular voltage recording trace for a muscle fiber cell. The dip in the voltage graph occurs after the insertion of the pipette into the cell and reflects the resting membrane voltage of the cell in that particular potassium solution. These membrane voltage traces represent the actual recordings of the membrane potential, which can then be compared to theoretical equations, such as the Nernst equation or the GHK equation. The Nernst equation is used to calculate the membrane potential of a cell given information about the concentrations of an ion intracellularly and extracellularly and its charge and assumes that the membrane is only permeable to one ion and thus does not account for the effect of other ions on the membrane potential.
Figure 2 displays the recorded membrane voltage and theoretical Nernst values with statistical differences. For both the recorded resting membrane potentials and the Nernst equation values…

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