An Ussing chamber is an apparatus for measuring epithelial membrane properties. It can detect and quantify transport and barrier functions of living tissue. The Ussing chamber was invented by the Danish zoologist and physiologist Hans Henriksen Ussing in 1946.''The Ussing Pulse project'' (goto.glocalnet.net)
/ref> The technique is used to measure the short-circuit current as an indicator of net

ion transport In biology, a transporter is a transmembrane protein that moves ions (or other small molecules) across a biological membrane to accomplish many different biological functions including, cellular communication, maintaining homeostasis, energy produc ...

taking place across an

epithelium Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...

. Ussing chambers are used to measure ion transport in native tissue, such as gut

mucosa A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is ...

, and in a monolayer of

cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...

grown on permeable supports.

Function

The Ussing chamber provides a system to measure the transport of ions, nutrients, and drugs across various epithelial tissues,''A guide to Ussing chamber studies of mouse intestine'' (Am J Physiol Gastrointest Liver Physiol. Jun 2009; 296(6): G1151–G1166. Published online Apr 2, 2009.)
/ref> (although can generate false-negative results for lipophilic substances). It consists of two halves separated by the epithelia (sheet of mucosa or monolayer of epithelial cells grown on permeable supports). Epithelia are polar in nature, i.e., they have an apical or mucosal side and a basolateral or serosal side. An Ussing chamber can isolate the apical side from the basolateral side. The two half chambers are filled with equal amounts of symmetrical

Ringer solution Ringer's solution is a solution of several salts dissolved in water for the purpose of creating an isotonic solution relative to the body fluids of an animal. Ringer's solution typically contains sodium chloride, potassium chloride, calcium chlo ...

to remove chemical, mechanical or electrical driving forces. Ion transport takes place across any epithelium. Transport may be in either direction. Ion transport produces a potential difference (voltage difference) across the epithelium. The voltage is measured using two voltage electrodes placed near the tissue/epithelium. This voltage is cancelled out by injecting current, using two other current electrodes placed away from the epithelium. This short-circuit current (Isc) is the measure of net ion transport. Measuring epithelial ion transport is helped by Ussing chambers. The voltage result from this ion transport is easy to accurately measure. The epithelium pumps ions from one side to the other and the ions leak back through so-called tight junctions that are situated between the epithelial cells. To measure ion transport, an external current is applied. Simply cancelling the voltage underestimates the true value. This is corrected by a short circuit at the voltage measuring electrodes. The resistance between the external voltage electrodes must be considered. The Isc underestimates the ion transport: the error can be as much as 10-fold. The type of chambers suggested by Ussing produces large errors. This error is often estimated by measuring the voltage without tissue present, leading to uncertain values. Better methods involve using alternating current in the form of sinuous-shaped current using several frequencies,

square wave A square wave is a non-sinusoidal periodic waveform in which the amplitude alternates at a steady frequency between fixed minimum and maximum values, with the same duration at minimum and maximum. In an ideal square wave, the transitions b ...

pulses, sharp impulses and random noise.

Types

The main types of Ussing chamber systems are:''Ussing Chamber Systems'' (harvardapparatus.com)
(PDF)''Ussing Chamber Systems'' (physiologicinstruments.com)
/ref> * The Classic chamber system (as designed by Ussing). * The Self-contained chamber system (the full apparatus within a single block) * The Multi-channel chamber system (2 to 24 independent chambers combined)

References

{{reflist

External links

Biography of The Royal Society: Hans Henriksen Ussing
(PDF; 1,1 MB)
''A guide to Ussing chamber studies of mouse intestine'' (Am J Physiol Gastrointest Liver Physiol. Jun 2009; 296(6): G1151–G1166. Published online Apr 2, 2009.)
Physiology Electrophysiology