Anion transport as related to hemoglobin A1c in erythrocytes of diabetic children.

We determined chloride and bicarbonate transport [Jcl and Jbic, nmol/(cm2.s)] under physiological conditions (Cl- 110 and HCO3- 25 mmol per liter, respectively, pH 7.4, 38 degrees C) across the erythrocyte membrane in blood samples from 12 diabetic (Jcl 26.1, SD +/- 3.7, n = 24; Jbic 7.6, SD +/- 0.9, n = 19) and 10 non-diabetic children (Jcl 30.6, SD +/- 4.6, n = 16; Jbic 7.3, SD +/- 1.0, n = 20) with mean hemoglobin A1c values of 11.08% (SD +/- 2.45%) and 5.36% (SD +/- 0.25%), respectively. The concentration of HbA1c, which also reflects the degree of glycation of the membrane proteins, differed significantly (P greater than 0.001) between the two groups, whereas there was no significant variation (P greater than 0.1) in Jcl and Jbic. We conclude that glycation of the integral transport protein in the erythrocyte membrane, capnophorin (also called "band 3"), which mediates a tightly coupled anion exchange, does not change the capacity of the transport system under physiological conditions. Thus the rate-limiting step of the exploitation of the CO2 transport capacity of the blood is not impaired in diabetics and consequently does not endanger the compensatory hyperventilation after ketoacidosis.