The large-conductance potassium ion channel of rabbit corneal epithelium is blocked by quinidine.

Basal layers of the rabbit corneal epithelium contain a large-conductance potassium ion (K+) selective channel (160-170 pS in 150 mM KCl). This channel previously was shown to be blocked by cesium and barium ions applied to its outer surface. By direct patch clamp experiments, it is shown that the channel also is blocked by quinidine in the 0.1-1 mM range when applied either to the outside or inside of membrane patches containing these channels. This additional pharmacologic tool should aid in identifying the individual currents that compose the macroscopic currents from corneal epithelial cells and eventually should help to provide a detailed assessment of their function.