来源

Erythropoietin, EPO，促红细胞生成素，属于集落刺激因子（Colony-stimulating factor, CSF），是机体红细胞生成的主要刺激物。

缺氧条件可刺激EPO生成增加。

Erythropoietin (EPO) is a ~34-kDa glycoprotein made mainly in the kidney by fibroblast-like type I interstitial cells in the cortex and outer medulla.

肾（90%-95%）
肾外，肝（Kupffer cells）
In fetal life, the liver rather than the kidney produces EPO. Even in the adult, Kupffer cells in the liver produce some EPO.

调节

Four lines of evidence indicate that the stimulus for EPO synthesis is a decrease in local P_O₂

First, EPO synthesis increases with anemia. (贫血)
Second, EPO production increases with lowered renal blood flow.
Third, EPO synthesis increases with central hypoxia (i.e., low arterial P_O₂), such as may occur with pulmonary disease or with living at high altitude (see p. 1231). 4In all three of these cases, local P_O₂ falls as tissues respond to a decrease in O₂ delivery by extracting more O2 from each volume of blood that passes through the kidney.
Finally, EPO production increases when hemoglobin has a high O₂ affinity. Here, the renal cells must lower P_O₂ substantially before O₂ dissociates from hemoglobin. Thus, mutant hemoglobins with high O₂ affinities, stored blood (which has low 2,3-DPG levels), and alkaline blood all lead to increased EPO production.
贫血、肾血流量降低、缺氧、高O₂亲和力

Other agents stimulate EPO production

For example, prostaglandin E₂ (PGE₂) and adenosine appear to stimulate EPO synthesis by increasing intracellular levels of cAMP. Norepinephrine and thyroid hormone also stimulate EPO release. Finally, androgens stimulate—whereas estrogens inhibit—EPO synthesis, which explains at least in part why women in their childbearing years have lower hematocrit levels than men do.

prostaglandin E₂ (PGE₂) -> cAMP+
adenosine
androgens(雄激素促进) estrogens（雌激素抑制）
促进红细胞生成
雄激素、甲状腺激素、肾上腺皮质激素、生长激素
抑制红细胞生成
雌激素、转化生长因子b，干扰素γ，肿瘤坏死因子

Downstream pathway

Acts through a tyrosine kinase–associated receptor.