Ion Channels / Ion Channels (PDF)

In the past few years, the scientific community has witnessed rapid and significant progress in the study of ion channels. Technological advance­ ment in biophysics, molecular biology, and immunology has been greatly accelerated, making it possible to conduct experiments that were deemed very difficult if not impossible in the past. For example, patch-clamp tech­ niques can now be used to measure ionic currents generated by almost any type of cell, thereby allowing us to analyze single-channel events. It is now possible to incorporate purified ion channel components into lipid bilayers to reconstitute an "excitable membrane." Gene cloning and monoclonal antibody techniques provide us with new approaches to the study of the molecular structure of ion channels. A variety of drugs have now been found or are suspected to interact with ion channels to exert therapeutic effects. In addition to the classical exam­ ples, as represented by local anesthetics, many other drugs, including cal­ cium antagonists, psychoactive drugs, cardiac drugs, and anticonvulsants, have been shown to alter the ion channel function. For certain pesticides such as pyrethroids and DDT, sodium channels are clearly the major target site. Many diseases of excitable tissues are known to be associated with, if not caused by, dysfunction of ion channels; these include cardiac ar­ rhythmias, angina pectoris, cystic fibrosis, myotonia, and epilepsies, to men­ tion only a few. Channel dysfunction can now be studied due to theoretical and technological developments in this area.