An ionocyte (formerly called a chloride cell) is a mitochondrion-rich cell within ionoregulatory organs of animals, such as teleost fish gill, insect Malpighian tubules, crustacean gills, antennal glands and maxillary glands, and copepod Crusalis organs. [1] These cells contribute to the maintenance of optimal osmotic, ionic, and acid-base levels within metazoans. In aquatic invertebrates, ionocytes perform the functions of both ion uptake and ion excretion. [2] In marine teleost fish, by expending energy to power the enzyme Na+/K+-ATPase and in coordination with other protein transporters, ionocytes pump excessive sodium and chloride ions against the concentration gradient into the ocean. [3] [4] [5] Conversely, freshwater teleost ionocytes use this low intracellular environment to attain sodium and chloride ions into the organism, and also against the concentration gradient. [3] [5] In larval fishes with underdeveloped / developing gills, ionocytes can be found on the skin and fins. [6] [7] [8]
Marine teleost fishes consume large quantities of seawater to reduce osmotic dehydration. [9] The excess of ions absorbed from seawater is pumped out of the teleost fishes via the ionocytes. [9] These cells use active transport on the basolateral (internal) surface to accumulate chloride, which then diffuses out of the apical (external) surface and into the surrounding environment. [10] Such mitochondrion-rich cells are found in both the gill lamellae and filaments of teleost fish. Using a similar mechanism, freshwater teleost fish use these cells to take in salt from their dilute environment to prevent hyponatremia from water diffusing into the fish. [10] In the context of freshwater fish, ionocytes are often referred to as "mitochondria-rich cells", to emphasis their high density of mitochondria. [11]
An ionocyte (formerly called a chloride cell) is a mitochondrion-rich cell within ionoregulatory organs of animals, such as teleost fish gill, insect Malpighian tubules, crustacean gills, antennal glands and maxillary glands, and copepod Crusalis organs. [1] These cells contribute to the maintenance of optimal osmotic, ionic, and acid-base levels within metazoans. In aquatic invertebrates, ionocytes perform the functions of both ion uptake and ion excretion. [2] In marine teleost fish, by expending energy to power the enzyme Na+/K+-ATPase and in coordination with other protein transporters, ionocytes pump excessive sodium and chloride ions against the concentration gradient into the ocean. [3] [4] [5] Conversely, freshwater teleost ionocytes use this low intracellular environment to attain sodium and chloride ions into the organism, and also against the concentration gradient. [3] [5] In larval fishes with underdeveloped / developing gills, ionocytes can be found on the skin and fins. [6] [7] [8]
Marine teleost fishes consume large quantities of seawater to reduce osmotic dehydration. [9] The excess of ions absorbed from seawater is pumped out of the teleost fishes via the ionocytes. [9] These cells use active transport on the basolateral (internal) surface to accumulate chloride, which then diffuses out of the apical (external) surface and into the surrounding environment. [10] Such mitochondrion-rich cells are found in both the gill lamellae and filaments of teleost fish. Using a similar mechanism, freshwater teleost fish use these cells to take in salt from their dilute environment to prevent hyponatremia from water diffusing into the fish. [10] In the context of freshwater fish, ionocytes are often referred to as "mitochondria-rich cells", to emphasis their high density of mitochondria. [11]