The oxygen transport system of red blood cells during diabetic ketoacidosis and recovery

Abstract

Daily evaluations of 8 newly detected ketoacidotic diabetics showed the Bohr-effect of haemoglobin to be decreased by 50% while erythrocyte 2,3-DPG was decreased below 10 μmoles/g Hb. 2,3-DPG correlated strongly with pH during acidosis and with plasma inorganic phosphate (Pi) subsequently to the first insulin administration. Oxygen affinity of haemoglobin, measured as P₅₀ act pH, was unchanged in ketoacidosis compared to the time before discharge. After correction of acidosis, however, P₅₀ act pH fell strikingly (p < 0.001) and remained decreased up to 7 days depending upon the resynthesis of 2,3-DPG in relation to Pi. The Hill-coefficient n reflecting the slope of the oxygen dissociation curve was diminished in ketoacidosis (p < 0.005), and decreased further after pH-normalization (p < 0.005). There was a close association of n with 2,3-DPG (p < 0.001) and additionally with Pi at 2,3-DPG-levels below 10 μmoles/ g Hb. Based on these findings a decreased erythrocyte oxygen release of one fifth during acidosis and more than one third after pH-correction can be hypothesised. In view of the intimate relation of Pi to the oxygen transport system it is suggested that treatment of ketoacidosis should include Pisubstitution.