Use the data in the table of equilibrium potentials handed out in class.

1.  Suppose the external potassium concentration in a mammalian cell is increased by a factor of 10.  What is the new value of the equilibrium potential for potassium?

2. At 10 degrees Celcius, a cell contains 80 mM sodium inside and the extracellular medium has a concentration of 100 mM.  What is the equilibrium potential for sodium?

3. When a mammalian cell is at rest, the permeabilities of potassium, sodium and chloride ions have the ratio Pk:Pna:Pcl = 1:0.01:0.1 but when the voltage is increased the permeabilities change to Pk:Pna:Pcl = 1:18:0.1.  Use the Goldman-Hodgkin-Katz Equation to compute the resting potential and the potential after voltage is increased for this cell.