Studies of Radioiron Utilization and Erythrocyte Life Span in Rats Following Thermal Injury 1

Abstract

The anemia which develops following thermal burns and the occurrence of a continuing anemia in burned patients and animals has been a frequent finding (1-4). Studies in this laboratory have indicated that in burned rats there is a rapid reduction in circulating red cell volume following high intensity radiant energy thermal burns (4). This reduction in red blood cell volume is followed by a period of increased red cell production as shown by the return of the circulating red cell volume to normal and by a significant reticulocytosis. Clinical studies in severely burned patients (2, 3) have revealed evidence of an immediate reduction in the circulating red cell volume and frequently a continuing reduction of the red cell volume. METHODSSix-week-old female albino rats of the Sprague-Dawley strain from the Laboratory colony were used. These rats weighed between 140 and 180 gm. at the time of burning. They were housed in individual wire cages and allowed free access to Purina chow and water. All animals were depilated by the method of Kuhl, Sheline, and Alpen (6). They were anesthetized with Nembutal@9 sodium (4.5 mg. per 100 gm. body weight subcutaneously) 4 days later and burned with a high intensity carbon arc source (7) by a method previously described. The burns produced were approximately 25 per cent of the total body area, and were similar, grossly and histologically, to the "white" burn described by 1 The opinions or assertions contained herein are those of the writers and are not to be construed as official or reflecting the views of the Navy Department or the Naval Establishment at large. Sheline, Alpen, Kuhl, and Ahokas (7). After two to three weeks the gray leathery eschar separated, leaving a raw, relatively clean, partially re-epithelialized area. Further epithelialization occurred in the next six to ten weeks so that by the end of the observation period (90 days) the burn areas had healed. Superficial infection of the lesion was a usual finding, but no significant surface loss of blood or fluid was observed.Days 2, 7 and 15 after burning were selected for studies of utilization of tracer doses of radioiron. On these days a similar number of depilated control rats were prepared which were anesthetized and similarly treated except for burning.At the appropriate time after burning, each animal was given a standard dose of 0.6 ml. of a sodium citrate buffered FeCl, solution, which contained 3 to 10 ,c. ofFe in approximately 6 to 20 pg. of total iron. The amount of radioactivity and the specific activity of the injected iron was the same for each group but varied among the various experimental trials. The Fe used was FeCl obtained from Oak Ridge National Laboratory and contained less than 10 per cent of Fe". The tracer dose was injected into the surgically exposed external jugular sinus. The surgical wound was closed with skin clips and healed promptly. Blood samples were taken at six hours and days 1, 2, 3, 5, and 7 following injection of the tracer and at weekly intervals thereafter. Blood samples were ...

Studies of red cell life span in the rat

“…These results are in general agreement with those of other recently reported studies of red cell survival in the rat with "4C-labelled cells (Van Dyke, Asling, Berlin & Harrison, 1955) and with 59Fe-labelled cells (Burwell et al 1953;Davis et al 1955). However, a direct comparison with the values quoted by these workers is not possible, since they have based their estimates of mean life span on the time at which the circulating radioactivity fell to the 50 % level, and have made no attempt to assess the relative importance of random destruction and senescence.…”

“…However, a direct comparison with the values quoted by these workers is not possible, since they have based their estimates of mean life span on the time at which the circulating radioactivity fell to the 50 % level, and have made no attempt to assess the relative importance of random destruction and senescence. Burwell et al (1953) remark that destruction appears predominantly random in nature in the rat and evidence of initial random loss also appears in the experimental data of Berlin et al (1953) and Davis et al (1955). On the other hand, no random destruction can be observed in the results obtained by Berlin & Lotz (1951), Berlin, Meyer & Lazarus (1951), Fryers & Berlin (1952) or Van Dyke et al (1955) on normal rats.…”

“…Intravenously injected 59Fe by contrast is more rapidly incorporated into red cell precursors in the erythropoietic tissues. However, since under normal conditions iron returned to the metabolic pool from destroyed red cells is largely re-utilized for new taemoglobin synthesis (Gibson, Aub, Evans, Peacock, Irvine & Sack, 1947) it is Escober & Baldwin (1934) Creskoff & Fitzhugh (1937) Harne, Lutz & Davis (1938) Ponticorvo, Rittenberg & Bloch (1949) Berlin, Huff & Hennessy (1951Berlin, Meyer & Lazarus (1951 Berlin & Lotz (1951) Fryers & Berlin (1952) Berlin, Van Dyke & Lotz (1953) Burwell, Brickley & Finch (1953) Davis, Alpen & Davis (1955) Van Dyke, Asling, Berlin & Harrison (1955) Donohue, Motulsky, Giblett, Pirzio-Biroli, Viranuvatti & Finch (1955) Giblett, Motulsky, Casserd, Houghton & Finch (1956) Hall, Nash & Hall (1957) The use of 51Cr in red cell survival studies is complicated by the fact that the 51Cr concentration in the blood falls more rapidly than would be expected from red cell destruction alone, a finding usually explained in terms of a slow elution of the isotopic label from the red cells in the circulation. Measurements of the 5lCr content of the blood must therefore be corrected for elution loss if true survival is to be estimated.…”

“…Most workers define this index as the time after which 50 % of newly emerging red cells have been destroyed, and measure it as the time for the circulating radioactivity to fall to one half of its maximum value (Davis et al 1955), or if re-utilization is significant, to a level midway between the maximum value and final value (Burwell et al 1953). It should, however, be pointed out that the quantity thus defined is a median life span and will only be equal to the mean if the frequency distribution of life span is symmetrical.…”

A Mild Transient Decrease of Peripheral Red Blood Cell Counts Induced by a Suprapharmacological Dose of Pegylated Human Megakaryocyte Growth and Development Factor in Rats

“…Those authors hypothesized that pharmacologically extremely high doses of PEG-rHuMGDF might result in the discordant generation of megakaryocyte mass followed by the suppression of the production of erythropoiesis and a decrease of the red blood cell counts. However, the lifespan of a red blood cell (50±70 days) is relatively long compared with those of other types of blood cells (Berlin et al 1951;Burwell et al 1953;Davis et al 1955). Therefore, it is unlikely that the decrease of peripheral red blood cell counts caused by high doses of PEG-rHuMGDF is due only to the suppression of erythropoiesis.…”