Cation permeation through connexin 43 hemichannels is cooperative, competitive and saturable with parameters depending on the permeant species

► Kinetics of permeation through connexin 43-EGFP hemichannels (Cx43-EGFP HCs) were evaluated in divalent cation-free solutions. ► Levels of Cx43-EGFP at the cell periphery and rate of dye uptake were directly related. ► The rate of uptake of each dye reached saturation consistent with a facilitated transport mechanism. ► Before saturation, the relation between rate of uptake and concentration of each dye was sigmoidal with Hill coefficients >1, indicating positive cooperativity of transport at low concentrations.