Inorganic phosphate accelerates hemoglobin A1c synthesis.
The effects of inorganic phosphate (Pi), 2,3-diphosphoglycerate (2,3-DPG) and glucose-6-phosphate (G-6-P) on labile and stable hemoglobin A1c (HbA1c) synthesis were studied. After a 75 gram oral glucose administration, the rate of labile or stable HbA1c synthesis decreased in parallel to the decrease in plasma Pi concentrations. In in vitro incubations of red blood cell suspensions or hemoglobin preparations with glucose, Pi proportionally increased the rate of labile or stable HbA1c synthesis. The increase in 2,3-DPG caused by Pi explained only one fiftieth of the increased rate of labile HbA1c synthesis, and G-6-P did not affect HbA1c synthesis. The kinetic analysis of the effect of Pi showed the unchanged rate constant [K1], the decreased rate constant [K-1], and the increased rate constant [K2]. Based on these data it is concluded that Pi in its physiological range directly increases hemoglobin glycation by decreasing labile HbA1c dissociation and accelerating the Amadori rearrangement for stable HbA1c synthesis, and that Pi should be taken into account when using HbA1c to evaluate diabetic control.
Clinical Laboratory, Kensei Sohgoh Hospital, Ibaraki, Japan.
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Kunika
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Itakura
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Yamashita
D019794:2,3-Diphosphoglycerate; D004163:Diphosphoglyceric Acids / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019298:Glucose-6-Phosphate; D005958:Glucosephosphates / Q000494:pharmacology; D006442:Glycated Hemoglobin / Q000096:biosynthesis*; D006801:Humans; D007700:Kinetics; D010710:Phosphates / Q000494:pharmacology*
D019794:2,3-Diphosphoglycerate; D004163:Diphosphoglyceric Acids; D019298:Glucose-6-Phosphate; D005958:Glucosephosphates; D006442:Glycated Hemoglobin; D010710:Phosphates