Erythrocytes gluconeogenesis

Vitamin B6-coenzyme is involved in a variety of reactions, e.g., in the immune system, gluconeogenesis, erythrocyte fimction, niacin formation, nervous system, lipid metabolism, and in hormone modulation/gene expression [1, 2]. 

Lactate as a precursor for gluconeogenesis is mainly derived from muscle (see Cori cycle, p. 338) and erythrocytes. LDH (see p. 98) oxidizes lactate to pyruvate, with NADH+H" formation. 

The effects of insulin on carbohydrate metabolism are discussed on p. 158. In simplified terms, they can be described as stimulation of glucose utilization and inhibition of gluconeogenesis. In addition, the transport of glucose from the blood into most tissues is also insulin-dependent (exceptions to this include the liver, CNS, and erythrocytes). 

The main precursors of gluconeogenesis in the liver are lactate from anaerobically working muscle cells and from erythrocytes, glucogenic amino acids from the digestive tract and muscles (mainly alanine), and glycerol from adipose tissue. The kidney mainly uses amino acids for gluconeogenesis (Glu, Gin see p.328). 

In mammals, gluconeogenesis in the liver and kidney provides glucose for use by the brain, muscles, and erythrocytes. 

In addition to these anti-inflammatory and immunosuppressive activities of pain control, oral corticosteroids have several other properties that make them useful as multipurpose adjuvant analgesics, especially in patients with pain associated with chronic disease or cancer. The mechanisms of these effects are less well worked out but corticosteroids also stimulate the erythroid cells of bone marrow and prolong the survival time of erythrocytes and platelets. They promote gluconeogenesis and protein catabolism. They reduce chemotherapy-induced nausea and vomiting, and alleviate dyspnea, effusion... 

FAs from the breakdown of TAG cannot be used for gluconeogenesis, rather they are oxidized in tissues to produce acetyl CoA. Acetyl CoA inhibits the conversion of pyruvate (from glycolysis) to acetyl CoA. Therefore glucose is spared, and FAs are used as a metaboHc fuel instead. The surplus acetyl CoA may exceed the capacity of the TCA cycle, and therefore is converted to KBs. KBs are metaboHzed by most tissues except erythrocytes, which can only use glucose. 

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