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Membrane and Transepithelial Potential

by Thad Wilson, PhD
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    How do we measure membrane potential? In a normal, symmetrical, or general cell, we put a little recording electrode within the cell and have a secondary electrode in a bath or in the fluid around it. That gives us our membrane potential. Epithelial tissue is different and that it has a number of different membrane potentials. The apical membrane has a membrane potential, the basolateral membrane has a membrane potential, and there’s a membrane potential across the whole epithelial cell itself. So we have three membrane potentials to take into account: the apical, the basolateral, and the complete endothelial cell’s membrane potential from one side to the other. So let’s go through some examples to practice this because this is a very different way of looking at voltages. It’s both across the membrane, across the second membrane, and then across the whole cell line. If we have an apical membrane voltage of let’s say minus 60 millivolts, we have a basolateral voltage of about minus 80 millivolts, therefore, there is a 20-millivolt difference between those two sides. So, it’s possible to involve ions differently that might want to move across the whole entire tissue that don’t necessarily want to move across one membrane or the other. Let’s keep going through some examples of this. Let’s use the transport of sodium and chloride as an example. If we have a voltage that is set up by a sodium-potassium ATPase, we have sodium traveling in across the apical membrane and then maybe potassium traveling across the basolateral. It can set up a voltage difference across the membrane and that voltage difference will want to drive chloride across through those tight junctions. Without the transepithelial voltage difference, the chloride would not want to travel in this direction. So it’s traveling towards a negative...

    About the Lecture

    The lecture Membrane and Transepithelial Potential by Thad Wilson, PhD is from the course Membrane Physiology.


    Included Quiz Questions

    1. Potassium
    2. Chloride
    3. Phosphate
    4. Oxide
    5. Iodide
    1. Three
    2. One
    3. Two
    4. Four
    5. None
    1. -20 mV
    2. -30 mV
    3. -40 mV
    4. -10 mV
    5. 0 mV
    1. ...negative...positive
    2. ...positive...negative
    3. ...negative...negative
    4. ...positive...positive
    5. ...negative...unchanged
    1. ...more negative voltage at the apical membrane
    2. ...more positive voltage of the apical membrane
    3. ...more positive voltage of the basolateral membrane
    4. ...more negative voltage of the basolateral membrane
    5. ...more positive transepithelial gradient

    Author of lecture Membrane and Transepithelial Potential

     Thad Wilson, PhD

    Thad Wilson, PhD


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