Where is erythropoietin released

Erythropoietin EPO is a hormone that is produced predominantly by specialised cells called interstitial cells in the kidney. Once it is made, it acts on red blood cells to protect them against destruction. At the same time it stimulates stem cells of the bone marrow to increase the production of red blood cells. Erythropoeitin testing in sport.

Blood sample being tested for the presence of the performance-enhancing hormone erythropoeitin. Although the precise mechanisms that control the production of erythropoietin are poorly understood, it is well known that specialised cells in the kidney are capable of detecting and responding to low levels of oxygen hypoxaemia through increased production of erythropoietin. When there is sufficient oxygen in the blood circulation, the production of erythropoietin is reduced, but when oxygen levels go down, the production of erythropoietin goes up.

This is an adaptive mechanism because it facilitates the production of more red blood cells to transport more oxygen around the body, thus raising oxygen levels in the tissues. For example, when moving in to a high altitude the air pressure drops and this can cause hypoxia that stimulates an increase in erythropoietin production. In low oxygen states, people risk developing hypoxia - oxygen deprivation. Hypoxia can also occur when there is poor ventilation of the lungs such as occurs in chronic lung disease, emphysema and in cardiovascular disease.

Excess erythropoietin results from chronic exposure to low oxygen levels or from rare tumours that produce high levels of erythropoietin. Galson, D. PubMed Abstract Google Scholar. Goldberg, M. The regulated expression of erythropoietin by two human hepatoma cell lines.

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The major site of Epo production is the kidney, while the liver is the main extrarenal site of Epo production. Within these organs, the cells synthesizing Epo were identified by using in situ hybridization in hypoxic animals with an increased Epo mRNA expression.

Epo-producing cells in the kidney were peritubular cells, most likely endothelial cells of the cortex and outer medulla. This hormone is synthesized in the kidney and its secretion is regulated by the amount of oxygen delivered to that organ.

Erythropoietin was one of the first drugs produced through recombinant DNA technology and is widely used in conditions where red blood cell production is deficient. In the fetus, it is synthesized in the liver, but production later switches almost exclusively to the kidney. Within the kidney, erythropoietin is produced by interstitial fibroblast-like cells that surround the renal tubules. When blood oxygen concentration is normal normoxia , synthesis of erythropoietin occurs in scattered cells located predominantly in the inner cortex, but under conditions when blood oxygen is deficient hypoxia , interstitial cells within almost all zones of the kidney begin to produce the hormone.

This is an interesting concept - increased production of erythropoietin is due to an increase in the number of cells that produce it rather than an increase in the level of synthesis by particular endocrine cells.

Under hypoxic conditions, for example with severe anemia, the kidneys can increase production of erythropoietin more than fold over normal.