Red blood cell wide variety of endogenous mediators and xenobiotics. Excessive eryptosis is observed in red blood cells lacking the cGMP-dependent protein kinase type I or the AMP-activated protein kinase AMPK. Inhibitors of eryptosis include erythropoietin, nitric oxide, catecholamines and high concentrations of urea. Much of the resulting breakdown products are recirculated in the body. The heme constituent of hemoglobin are broken down into iron (Fe) and biliverdin. The biliverdin is reduced to bilirubin, which is released into the plasma and recirculated to the liver bound to albumin. The iron is released into the plasma to be recirculated by a carrier protein called
Packed red blood cells are used in these situations, since they are unlikely to cause a reaction. A potentially fatal reaction is possible if the recipient has pre-existing antibodies, and uncrossmatched blood is only used in dire circumstances. Since O negative blood is not common, other blood types may be used if the situation is desperate. Most frequently, whole blood is collected from a blood donation and is spun in a centrifuge. The red blood cells are denser and settle to the bottom, and the majority of the liquid blood plasma remains on the top. The plasma is separated and the red blood cells