Stimuli for Erythropoiesis?

[Ryu02ETL]

In Goljan's Path 3rd ed (p.191), it's stated that a left-shifted O2-binding curve is a stimulus for EPO. However, the other stimuli (hypoxemia, severe anemia, high altitude) are associated with a right-shifted O2-binding curve.

Can anyone explain why a left-shifted curve is associated with EPO synthesis/release?

...or is this a typo?

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[jeesapeesa]

In Goljan's Path 3rd ed (p.191), it's stated that a left-shifted O2-binding curve is a stimulus for EPO. However, the other stimuli (hypoxemia, severe anemia, high altitude) are associated with a right-shifted O2-binding curve.

Can anyone explain why a left-shifted curve is associated with EPO synthesis/release?

...or is this a typo?

less unloading to tissue = left shift. hypoxia = EPO increase

 

[turkeyjerky]

think of it this way: the less O2 the interstitial cells of the peritubular capillaries get, the more epo they release. so anything that decreases the amount of O2 they're exposed to, like anemia, low PaO2, fetal hemoglobin--the more epo gets produced and the more rbcs get made

 

[IMGUSMLEStep1]

left shift means hemoglobin is hogging all the Oxygen to itself, and isn't sharing any of it with the kidneys. The kidney is thus tricked into thinking that there isn't enough oxygen, and thus increases EPO secretion to compensate.

 

[Macguy86]

Left shift of the curve means that Hb is tightly binding to the oxygen. The interstitial cells of the peritubular capillaries in the renal cortex detects the decrease in O2 and secretes EPO. This is why newborns have a higher Hb count. HbF left shifts the O2 Curve, EPO is released, Hb is increased to about ~18.5

With hypoxemia, your body is consuming the O2 at a fast rate, so therefore you have an increase in H+ produced by metabolic reactions in your cells/tissues, which RIGHT shifts the curve to unload more O2 from Hb.


Both cases there is a decrease in O2 sensed by the interstitial cells and an increase is EPO. Hope this helps.

 

[Pegasus1731]

less unloading to tissue = left shift.

LESS released when LEFT

OMG you are my hero. I seriously could never keep this straight, and you just fixed it for me. L = L I can finally remember that now! Thank you!!!

 

[Ryu02ETL]

thanks to everyone that cleared this up.