Typical ion concentrations and permeabilities for mammalian membranes.

Ion Cell (mM) Blood (mM) Permeability (cm/s)
potassium 140 5 5 x 10-7
sodium 5-15 145 5 x10-9
chloride 4 110 1 x 10-8
X- (neg. macromol.) 138 9 0