Help: Nernst and reversal potentials

[madbeemer]

I know the following
ion/inside cell/outside cell
Cl- 5mM 150 mM
K+ 130mM 5mM
Na+ 20mM 140mM
Ca2+ 10^-4mM 2mM

How would I find the reversal potential for conductance equally permeable to sodium and potassium?
How do I find the reversal potential for a conductance equally permeable to sodium, potassium, and chlorine?
Also, how do I find the nernst potential for each ion at the below external and internal concentrations?

 

[madbeemer]

bump- for great justice!

 

[Blueshift5]

To find the reversal potential for conductance equally permeable to sodium and potassium, you would use the Goldman-Hodgkin-Katz equation, which takes into account the concentrations and permeabilities of each ion. In this case, the reversal potential would be around -50mV, which is the average of the Nernst potentials for sodium (-61mV) and potassium (-89mV).

For a conductance equally permeable to sodium, potassium, and chlorine, you would again use the Goldman-Hodgkin-Katz equation, but this time also taking into account the permeability of chloride. The reversal potential would be around -65mV, which is the average of the Nernst potentials for sodium, potassium, and chloride (-35mV, -89mV, and -61mV, respectively).

To find the Nernst potential for each ion at the given concentrations, you would use the Nernst equation, which takes into account the charge and concentrations of the ion. For Cl-, the Nernst potential would be around -63mV; for K+, it would be around -86mV; for Na+, it would be around +61mV; and for Ca2+, it would be around +120mV. These values represent the equilibrium potential for each ion, where there is no net movement of the ion across the membrane.