Chloride cell
Chloride cells are cells used for osmoregulation by many animal species that live in saline environments such as the ocean. All animals that have these cells secrete excess salt through them, which would otherwise disrupt their osmoregulation. For example, they allow them to drink sea water. The activity of these cells is controlled by both hormones and innervation .
Animals with chloride cells
Marine bony fish have these cells in their gill epithelia . Through these cells they can release the salt that they have ingested while drinking into the sea water. Also have cartilaginous fish such as sharks and marine stingrays these cells in their Rektaldrüsen. All marine birds have similar cells in the nasal glands that secrete a salty secretion. This allows these birds to keep their osmolarity , i.e. the salt content in their body fluids, constant by drinking salt water . The marine iguanas on the Galapagos Islands have no access to fresh water and are exposed to constant water loss due to solar radiation. By drinking sea water and excreting salt through these cells, the animals in this environment manage to keep their osmolarity at a suitable level.
Cellular Mechanism
The chloride cells are located in the epithelial tissue of the animals and are surrounded by so-called accessory cells, which are connected to them via end strips. These strips are permeable to sodium - ions . Several channels or transporters that are important for their function are located in the basolateral membrane of the chloride cells. A sodium-potassium pump provides, among ATP -Consumption, for a steep gradient sodium outside the cell. It pumps two potassium ions in and three sodium ions out. Chloride enters the cell via a sodium-potassium-chloride cotransporter in the basolateral membrane and flows into the surrounding medium through a channel on the apical membrane. Sodium follows from the extracellular fluid via the end strips, which results in a charge balance in the organism.