Ussing

Ussing is a Danish surname that is chiefly associated in physiology with the Ussing chamber, an experimental apparatus used to study transport across epithelial tissues. The chamber was developed by Danish physiologist Hans Christian Ussing and colleagues in the mid-20th century. It consists of two fluid-filled half-chambers separated by a thin sheet of epithelium mounted on a permeable support. Electrodes in each half-chamber measure the transepithelial potential difference, and when the tissue is short-circuited, the resulting short-circuit current reflects the net active ion transport across the epithelium. By applying controlled voltages, researchers can determine transepithelial conductance and distinguish active transport from passive diffusion.

Applications of the Ussing chamber span multiple epithelia, including intestinal, renal, and airway tissues, as well as other mucosal surfaces. It is used to quantify movements of ions such as sodium, chloride, and bicarbonate, assess paracellular permeability, and evaluate the effects of hormones, drugs, and toxins on epithelial transport. The method helped establish fundamental concepts of active transport and epithelial ion handling and has informed the study of transporter proteins and ion channels.

Legacy and variations of the technique remain foundational in physiology and pharmacology. Chambers of the Ussing type continue to be used in research and education to investigate epithelial transport processes, serving as a bridge between basic physiology and clinical understanding of fluid and electrolyte balance.