Potassium channels and airway function: new therapeutic prospects.

Potassium (K+) channels have long been associated with recovery of excitable cells after depolarisation and drugs that block these channels, such as tetraethylammonium and 4- aminopyridine, cause an increase in excita- bility. In airway smooth muscle these K+ channel blocking drugs result in spontaneous action potentials and a reduced threshold of excitation,'2 which may be similar to the elec- trophysiological changes described in asth- matic airways.'