An Analytical Study of in Vivo Survival of Limited Populations of Animal Red Blood Cells Tagged With Radioiron

Abstract

Until recently, only a few studies (1-6) of red cell life span in a limited number of animal species had been made. These early studies, made by a variety of methods, gave estimates of red cell life span for certain species that varied widely (e.g. rabbit 8 to 42 days, dog 20 to 124 days). Recently, Finch and coworkers (7) employing radioiron, and Bale et al. (8) employing C a* have estimated the life span of the dog red cell to be 107 to 110 and 115 days, respectively. Harrison and associates (9) using radioiron, and Neuberger and Niven (10)using N15-1abeled glycine estimated the life span of rabbit red cells to be 62 to 75 days. Valentine and others (11) using N 15 have estimated the mean life span of the cat red cell at 77 days.The use of isotopes in tagging erythrocytes for in vivo survival studies is subject to certain criticism. Previous investigators (8,12,13) have shown that there is no apparent loss or exchange of the isotopes of iron, nitrogen, or carbon when once incorporated into the hemoglobin molecule. However, radioiron is rapidly and almost completely reutflized following red cell breakdown unless suppressed by the competition of greatly increased body stores of non-radioactive iron and continuous high levels of non-radioactive total serum iron (7,14). N 15 incorporated in the protoporphyrin of heine and C14-tagged globin are supposedly not reutilized in the formation of new hemoglobin. Nevertheless, red ceil survival curves based on these technics, published to date (8, 10,11,13,15), show considerable amounts (10 to 30 per cent of maximal uptake) of both N ~5 and C 1' persisting in circulating red cells for periods up to 200 days. In addition, the relatively slow uptake and early decline in the N is level (40 to 60 days) lead to great difficulty in estimating with an accuracy the average life span and variations in red cell life.Recent investigations (7-10) have revealed varying degrees of random destruction of red cells occurring in apparently healthy normal animals--a fact which further complicates in d~o survival studies. While isotope reutilization and random destruction

Storage Iron Kinetics. VII. A BIOLOGIC MODEL FOR RETICULOENDOTHELIAL IRON TRANSPORT

“…In these same animals, when the rate of change of plasma iron during the first 3 h of study was used, an even better correlation with the proportion of early release was observed (Fig. 3) A significantly better correlation was observed when early release is related to the rate of change in plasma iron (P < 0.001) than to the level of plasma iron (P < 0.01 (18,19) and a blood volume of 90 ml/ kg (20). Despite the fact that the normal rate of erythrocyte iron turnover was exceeded, a more than 10-fold increase of the iron load to above 100 Ag/kg produced no apparent difference in the pattern (2) where a single injection of 100 Ag nitrilotriacetic acid iron 3 h before injection of WDRBC was found to markedly depress the immediate release of RE iron and to proportionately increase the radioiron incorporation into ferritin.…”

Purine Nucleoside Phosphorylase Activity of Blood. I. Erythrocytes 1

“…If the same holds true for the dog, whose normal erythrocyte life span is about 100 days (22), the slow exponential type of decay curve of PNP activity over a period of about 70 days depicted in Figure 5 suggests that the increased PNP activity remained in the rapidly produced cells of the dog for the duration of their survival. SUMMARY 1.…”

THE POTENTIAL LIFE SPAN AND ULTIMATE SURVIVAL OF FRESH RED BLOOD CELLS IN NORMAL HEALTHY RECIPIENTS AS STUDIED BY SIMULTANEOUS Cr51 TAGGING AND DIFFERENTIAL HEMOLYSIS 1

“…for 45 mins. and correcting the resulting figure for the 3 per cent of the saline that had been shown to be trapped among the corpuscles under our conditions (4). The radioactivity of the red cell suspension was measured in a well type scintillation counter 2 after diluting 1: 100 with distilled water.…”