KIDNEY HORMONES

Formation of erythropoietin

This glycoprotein hormone as Kidney hormone becomes about in adults 90% in the kidney and to a small extent in the liver as well as in brain in fetuses, the hormone is mainly produced in the liver.
In the kidney, cells of the blood vessels (capillaries, endothelial cells) are responsible for production. You start synthesizing erythropoietin after going through the Factor HIF-1 (Hypoxia-inducible factor 1) were stimulated.
This factor depends directly on the oxygen pressure. If the pressure is low, the stability of the HIF-1 and thus the ErythropoietinFormation, at high pressure, however, HIF-1 shows instability, whereby the synthesis of the hormone is reduced. With regard to hormone synthesis, HIF-1 acts as a transcription factor.
By transcription of these hormones of the kidney one understands the translation of the Gene structure (DNS = Deoxyribonucleic acid) in proteins, in this case in the hormone erythropoietin. HIF-1 consists of two different subunits (alpha, beta). First, when there is a lack of oxygen, the alpha subunit of HIF-1 migrates into the cell nucleus and there binds to the beta subunit. The complete HIF-1 binds after the addition of two further factors (CREB, p300) to the corresponding part of the genome (DNA), where the information about the structure of the hormone erythropoietin resides. Due to its binding, HIF-1 enables the information to be read and thus translated into a protein structure. This is how the hormone is ultimately made.
The receptors of the hormone erythropoietin are more immature on the surface red blood cells (Erythroblasts), which is located in Bone marrow are located.

Illustration of the kidney

Figure: Flat section through a right kidney from the front

Renal cortex - Renal cortex

Renal medulla (formed by the
Kidney pyramids) -
Medulla renalis

Kidney bay (with filling fat) -
Renal sinus

Calyx - Calix renalis

Renal pelvis - Pelvis renalis

Ureter - Ureter

Fiber capsule - Capsula fibrosa

Kidney column - Columna renalis

Renal artery - A. renalis

Renal vein - V. renalis

Renal papilla
(Tip of the kidney pyramid) -
Renal papilla

Adrenal gland -
Glandula suprarenalis

Fat capsule - Capsula adiposa

You can find an overview of all Dr-Gumpert images at: medical illustrations

Regulation of erythropoietin

The hormone is produced depending on the oxygen supply in the blood. If there is only little oxygen (hypoxia), the release of erythropoietin occurs, which stimulates the erythroblasts to mature. Thus, more red blood cells are available as oxygen carriers in the blood and counteract hypoxia through the increased oxygen transport. If, however, there is enough oxygen, no erythropoietin is produced and the number of red blood cells is not increased (negative feedback). Overall, the red blood cells represent a marker for the oxygen saturation of the blood, as they bind the oxygen with the help of the hemoglobin they contain and transport it to various tissues via the bloodstream.

Effect of erythropoietin

The Erythropoietin the kidneys and liver regulate the oxygen levels in the blood. Specifically, this hormone acts on the transport of oxygen in the blood by causing the reproduction and maturation of the red blood cells (Erythrocytes) which transport oxygen in the blood. The erythropoietin, which in the brain is only in the blood vessels of the brain, as it is due to the so-called Blood-brain barrier cannot leave this room. Its function is not fully understood; it is believed that it protects nerve cells from damage when there is a lack of oxygen (neuroprotective effect).
In medicine there is artificial (genetically) manufactured erythropoietin application. In patients with Anemia (anemia) and Kidney failure, in which the kidneys are no longer able to produce the hormone itself, erythropoietin is administered to stimulate blood formation and in this way to eliminate renal anemia.
Even with anemia by one tumor or after chemotherapy the hormone erythropoietin is used.
In sport, the hormone erythropoietin is also used as prohibited doping. As the amount of red blood cells increases after taking this hormone, the oxygen-carrying capacity of the blood also increases at the same time. As a result, more oxygen reaches the muscles and other tissues, which means that the metabolism (for example for muscle movement) can work more efficiently and for longer. The result is a growing performance of the athletes.