[Transfer of monovalent cations across the isolated human amniotic membrane].

When the conductance and the bi-ionic potential are measured in vitro, monovalent cations are transferred according to a simple diffusion mechanism across the amnion (from the inside to the outside of the amniotic cavity or in the reverse direction) in channels with neutral or negative fixed sites. For equal concentration, the permeability to K+ is superior to that of Na+.