Ion channels are openings that exist within a cell that allow the passage of certain ions into a cell to regulate activity. It is believed that hundreds of different types of ion channels exist in the body, each with a distinct responsibility for sending a specific message, and that specific pacemaker channels exist in peripheral nerves as well as in the heart and the central nervous system. In the heart, for instance, signals generated by pacemaker channels stimulate the heart muscle to contract, and in the brain, they control sleep and waking. Made up of glycoproteins, or proteins with sugar molecules attached, pacemaker channels -- also known as HCN channels (Hyperpolarization activated, Cyclic Nucleotide-gated cation channels) -- allow the entrance of sodium ions into the cell based on the configuration of the protein. Entry of sodium ions can trigger electrical activity in both cardiac cells and neurons.
"We think we have only scratched the surface in this area, as pacemaker channels may also play a role in inflammatory pain as well as other types, " said Dr. Wickenden. "More research is needed before this will translate to patient benefit, but the better understanding we've gained of the mechanism can enable us to narrow our focus."