Increased ion traffic through non-specific cation pathways in the ageing human lens. Evidence from radiotracer fluxes studies.

86Rb efflux studies were carried out on normal human lenses in vitro. The data confirmed previous studies showing that 86Rb efflux increases with age. Removal of Ca2+ from the lens perifusate increased 86Rb efflux at all ages. The fractional increase above baseline was highest in the younger lenses, while the net increase of the 86Rb efflux induced by a Ca(2+)-free medium increased with age. This study supports the idea that Ca(2+)-sensitive, non-specific cation channels are present in the human lens and that their contribution to membrane permeability increases as the lens ages