Molecular Anatomy of Cardiac Ion Channels by Developing and Applying New Molecular Tools

点击翻译按钮获取中文摘要

Cardiovascular diseases are serious problems in health ranking the highest lethal rate in modern society. In order to diagonize the patients, reveal their causes, and establish better therapeutic methods, it is essential to reveal structures and functions of molecules that are relevant to cardiac excitation and propagation. We investigated three cardiac channels (Ca^<2+>channel, Na^+channel, and ATP-sensitive K^+channel) by various methods including chemical, biochemical, immunochemical, and electrophysiological techniques. The results obtained after 2 years works are summarized as follows.(1) We are succeeded in identifying the binding sites of a typical calcium antagonist (dihydropyridine) in Ca^<2+>channel by photoaffinity labeling with a newly synthesized reagent. The sites revealed were identical to the skeletal muscle counterpart, but several substitution in amino acids was observed in the sites. They may imply the 10-fold difference of binding affinity between the two channels.(2) A potential candidate protein of ATP-sensitive K^+channel was isolated by biochemical purification of the cardiac preparations that were photolabeled with a new glibenclamide derivative. Immunohisto-chemical experiments showed that the protein was localized in the membrane surface of the ardiac venticules.(3) Mexiletine analogs for photoaffinity labeling and antibody generation were synthesized as molecular probes of a typical class I anti-arrhythmic agent for cardiac Na^+channels.