The Hartzell Lab in the Department of Cell Biology at Emory University School of Medicine in Atlanta, GA (USA) studies the molecular mechanisms that cells use to regulate the movement of ions like sodium, potassium, calcium, and chloride across their membrane. Our focus is ion channel proteins that form aqueous pores across cell membranes. They are vital to the cell's ability to maintain and regulate the cell's internal ionic composition because ions do not easily cross the oily cell membrane. Ion channel pores are selective for different species of ions; that is, they have structures that allow only one or a few kinds of ions to enter them. Ion channels also have gates that open and close to control ion movement across the membrane. Channel gating can be controlled by various factors including membrane potential, chemicals and neurotransmitters, mechanical stretch, and heat. Ion channels are important in probably every physiological process, from the heart beat to the immune response. Our lab is interested in understanding the roles that ion channels in cell physiology and the molecular machinery that determines how channels open and close and conduct ions. Presently, our main interest is devoted to chloride channels. It is possible that more people have been killed by diseases that affect chloride channels than any other disease, because cholera, diarrheal diseases of infancy, and cystic fibrosis involve chloride channel function. Chloride channels are essential for fluid and salt secretion from epithelia, play a role in sensory transduction, regulate both cytosolic pH and the pH of intracellular organelles, control neuronal and cardiac excitability, and contribute to bone resorption by osteoclasts. In addition to cystic fibrosis and secretory diarrheas, a wide variety of diseases including cystic fibrosis, myotonias, osteopetrosis, deafness, kidney disorders, and neurodegenerative diseases are linked to defects in chloride channel function. Learn more.