The high resting permeability of the T system to
chloride relative to potassium
means that the resting potential (EM) will be heavily
weighted towards the chloride equilibrium potential (ECl)
which will remain relatively constant during
activity owing to the high [Cl] in the T system
and relatively large amount of Cl in ux needed to
change the [Cl]i
. For this reason, any inward ux of Cl
during the repolarizing phase of an AP has much less
effect on steady-state conditions than would a matching
outward ux of K