The production of 14CO following the administration of 2-[14C] glycine in normal subjects determined by an oxygen washout technique

The contributions of erythropoietic and nonerythropoietic haem turnover to the early labelle peak of endogenous CO formation in man

The endogenous production of 14CO during the first week after administration of glycine-2-14C (early labelled peak, ELP) was determined in 13 healthy subjects. The subjects were studied during normal, suppressed or stimulated erythropoiesis induced by hypertransfusion and phlebotomy, respectively. The production of 14CO was calculated from determinations of the specific activity of the body CO store and the endogenous production of CO. The incorporation of labelled glycine into circulating red cell haemo;globin haem was calculated from the maximal specific activity of haemoglobin haem and the total amount of Hb. The average ELP was 73.0 X 10(3) disintegrations per min (dpm) and the incorportion of glycine into circulating haemoglobin haem 491 X 10(3) dpm in controls. The ELP and the incorporation of glycine increased by 86% and 92%, respectively, in phlebotomized subjects and decreased by 37% and 62%, respectively, in hypertransfused subjects. A linear regression equation was calculated for the relationship between ELP and erythropoiesis, expressed as the incorportion of glycine into circulating haemoglobin haem. The residual ELP remaining in the absence of erythropoiesis was 24.9 X 10(3) dpm calculated from data of all the subjects, and 32.8 X 10(3) dpm calculated from data of controls and hypertransfused subjects only. In conclusion, erythropoietic haem turnover was found to contribute about 60% and nonerythropoietic (mainly hepatic) haem turnover about 40% of the ELP in man.

Quantification of ineffective erythropoiesis in megaloblastic anaemia by determination of endogenous production of 14CO after administration of glycine-2-14C

The determination of the early peak of 14CO production that results from haem turnover after administration of glycine-2-14C was studied in patients with pernicious anaemia. The accuracy of this technique in measuring ineffective erythropoiesis was assessed by comparison with other measurements of the severity of the disease. 6 patients were studied before specific treatment and 2 of these also after treatment. The endogenous production of 14 CO was calculated from determinations of the production of CO by a rebreathing technique and of the specific activity of CO washed out from the body CO store by oxygen breathing. The early labelled peak was increased 7-39 times compared to that in healthy control subjects and represented 35-86% of the total production of 14CO as compared to 13% in controls. The early labelled peak was significantly correlated to the Hb concentration, mean red cell volume and endogenous production of CO. 2 patients, twice examined, showed a moderately increased early labelled peak also after specific treatment. This was attributed to persistence of some ineffective erythropoiesis in 1 patient and possibly increased hepatic haem turnover in the other. The magnitude of the early labelled peak and the maximal activity of 14CO found in the samples of CO collected from the body CO store were significantly correlated. In conclusion, with the present method the early peak of 14CO reflected the ineffective erythropoiesis in patients with pernicious anaemia. The early labelled peak could be predicted from the maximal activity of 14CO found in the samples of CO washed out from the body CO store.