Gap Junctions and Heart Development

The function of gap junctions in propagation of the cardiac action potential is one of the best characterized roles for intercellular communication. Comprehending the part played by cell-to-cell dialogue in embryological processes, including development of the heart, has proven to be a more complex problem. Nonetheless, research at the conjunction of cardiac development and gap junctions is a diverse and fast-moving arena. Significant recent advances have resulted from mutational analysis or transgenic alterations of the genes encoding the subunits which comprise the gap junction channel-the connexin proteins (1-3). Such work has directly linked proper gap junction gene function to normal cardiac organogenesis and also implicated altered intercellular communication in certain congenital abnormalities of the heart. Of further interest is the suggestion that alteration to coupling patterns in the diseased mature heart may result from pathological reiteration of developmental processes involved in the cellular organization of gap junctions (4,5). Such insight may be clinically relevant, as disruptions to myocyte coupling patterns have been implicated in the genesis of arrhythmias and other disturbances of cardiac conduction (see chapter 8).