Biologists have discovered how an outer shield over T-type channels change the electrochemical signaling of heart and brain cells. Understanding how these shields work will help researchers eventually develop a new class of drugs for treating epilepsy, cardiovascular disease and cancer. The researchers discovered T-type channels in the pond snail, Lymnaea stagnalis, can shift from using calcium ions to using sodium ions to generate the electrical signal because of an outer shield of amino acids called a turret situated above the channel's entrance.