The reticulocyte-mediated release of iron and bicarbonate from transferrin: Effect of metabolic inhibitors

The effect of three groups of metabolic inhibitors on the incorporation of Fe and release of bicarbonate from transferrin by rabbit reticulocytes was measured. Inhibitors which affect reticulocyte Fe and transferrin uptake to the same extent (sodium arsenite, N-ethylmaleimide and iodoacetamide); those which inhibit reticulocyte Fe uptake to a greater extent than transferrin uptake (NaN₃, NaF, NaCN, rotenone, oligomycin, 2,4-dinitrophenol and cycloheximide); and compounds which after reticulocyte heme synthesis (CoCl₂, isonicotinic acid hydrazide and hemin) were used. In each case the effect on Fe incorporation and bicarbonate release was the sameThus, additional evidence has been obtained for the idea that the reticulocyte-mediated release of Fe and bicarbonate from transferrin are tightly coupled. The results are consistent with the hypothesis that an enzymatic attack on transferrin-bound bicarbonate is involved in the removal of Fe from transferrin by erythroid cells.     

The distribution of glucose and [14C]glucose between erythrocytes and plasma in the rat

1. Of the glucose in rat blood 79.8+/-3.3% (s.d.) was in the plasma. The variance was mostly due to differences between rats. 2. The concentration of glucose in erythrocyte water was 51+/-8% (s.d.) of that in plasma water. 3. The ratio (specific radioactivity in plasma)/(specific radioactivity in whole blood), i.e. the P/B ratio, was estimated for glucose at intervals after intravenous injection of [U-(14)C]glucose and [U-(14)C]fructose. The ratio differed from unity by more than the standard error of a single determination of the specific radioactivity of blood or plasma glucose except from 10 to 17min. after injection of [(14)C]glucose and from 22 to 30min. after injection of [(14)C]fructose. At all other times specific radioactivities in blood had to be corrected to give specific radioactivities in plasma. How to do so is described. 4. The P/B ratios were accounted for by a turnover of glucose in erythrocytes of 0.14mumole/min./ml. of erythrocytes. 5. Metabolism of glucose in rat erythrocytes is unlikely to be a major source of lactate.     

Dissociation of Intrinsic Factor from its Antibody: Application to Study of Pernicious Anaemia Gastric Juice Specimens

Intrinsic factor antibody may sometimes be concealed in the gastric secretions of pernicious anaemia subjects, being complexed with residual amounts of intrinsic factor.A method is described for dissociating intrinsic factor from its antibody. Antibody to the vitamin-B₁₂-binding site of intrinsic factor was identified in 16 (57%) out of 28 samples of pernicious anaemia gastric juice after dissociation but in only 10 before dissociation. There was no clear relationship between the incidence of antibody in the serum and in the gastric juice of these patients.     

Measurement of Glomerular Filtration Rate by Inulin Clearance without Urine Collection

A continuous infusion method for measuring inulin clearance (and hence glomerular filtration rate) which does not require urine collection has been re-evaluated and found to give satisfactory results. In two non-oedematous and anephric patients the plasma level of inulin became virtually constant four hours after a single intravenous dose, and hence this is the minimum time required for the infusion with this method.