POTASSIUM CHANNELOPATHIES

The molecular diversity of K+-selective channels far exceeds any other group of voltage- or ligand-gated channels, reflecting their early an cestral origin. This diversity is mirrored by the broad spectrum of ph ysiological functions subserved by these proteins. Potassium channels modulate the resting potential and action potential duration of neuron s, myocytes and endocrine cells and stabilize the membrane potential o f excitable and nonexcitable cells. In addition to channel diversity, differential cellular expression of K+ channels determines the specifi c electrical responses to stimuli in a particular cell or tissue. This study reviews the recent genetic and physiological studies of congeni tal disorders caused by mutations in genes encoding K+ channels. These include the human disorders of episodic ataxia with myokymia, long QT syndrome and Bartter's syndrome, and weaver ataxia in mice. An unders tanding of the molecular basis of these diseases could facilitate the discovery and development of specific pharmacological therapies. (C) 1 997 Elsevier Science Ltd.