Question

For a sodium permeable membrane and sodium concentration interior = 100mM and exterior = 80mM, the ion flux is ___ and the current is ___.

Answer 1

given,

interior concentration of Na+ = 100mM

exterior concentration of Na+ = 80mM

Ion flux = 2.3 (RT/zF) ln ( [Na+]out / [Na+] in)

taking the normal body temperature, 37oC as T,

then 2.3 RT/zF = 60mV

R = 8.314J/mol

T = 310K

z = 1

F = 96485 J/V/mol

putting the values to equation,

flux = 60 log ( [80]/ [100] )

= 60 log 0.8

= 60 x - 0.096

= 5.76

membrane potential = 61.5 x log ( [Na+]out / [Na+]in)

= 61.5 x log (80/100)

= 61.5 x log 0.8

= 61.5 x -0.096

= -5.904

Ionic current = channnel conductance x ( membrane potential - flux)

= 30 x (-5.904 + 5.76)

(* channel conductance of Na+ = 30)

= 30 x -0.144

= -4.32