On the Kinetics of Iron Absorption in Mice*

Gitlin, David; Cruchaud, A

doi:10.1172/jci104488

Cited by 46 publications

(19 citation statements)

References 10 publications

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“…This implies that an additional mechanism is operative in which the amount of metal in the perfusate is an important determining factor. A similar conclusion was reached by Bannerman, O'Brien, and Witts (16), and Gitlin and Cruchaud for iron absorption in the mouse (17). The inhibitory effect of iron on cobalt absorption, and cobalt on iron absorption, and the close similarity between the maximum transport velocity (V...) of the two metals in iron deficiency suggests that they compete for analogous binding sites in the transport system.…”

Section: Effect Of Administering Iron and Cobalt Togethersupporting

confidence: 77%

“…and Km in Table II for cobalt and iron under different experimental conditions are only approximate. The absence of a distinct plateau is probably due to the concomitant passive diffusion of small amounts of metal (17). This would have its greatest effect on the estimation of Vm.. when absorption was low, such as in iron overload, and therefore these values were not calculated.…”

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confidence: 99%

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Competitive nature of the intestinal transport mechanism for cobalt and iron in the rat

Thomson¹,

Valberg²,

Sinclair³

1971

J. Clin. Invest.

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A B S T R A C T Dose-and time-response studies were performed in iron-loaded and iron-deficient rats in order to define, (a) the kinetics of absorption of cobalt and iron, (b) the nature of the inhibitory effect of one metal on the absorption of the other, and (c) the effect of variations in body iron stores on these processes. The duodenum was perfused for 5-90 min with labeled solutions containing 5.0 mm iron or 5.0 mm cobalt. In ironloaded rats, the rate of cobalt absorption was constant for 90 min whereas the rate of iron absorption fell after 30 min. In comparison to these results, the rate of absorption of both metals was increased in iron deficiency, and was more rapid in the first 30 min than in the 30-90 min period.To determine the response to varying doses of metal, we perfused duodenal loops for 30 min with 0.1-10.0 mm solutions of either iron or cobalt. In both iron-loaded and iron-deficient groups, a greater proportion of the metals was absorbed from smaller than from larger doses. When iron and cobalt were perfused together in iron-deficient animals, cobalt competitively inhibited iron absorption, and conversely, iron reduced cobalt absorption. The apparent maximum transport velocity was similar for both metals, but the affinity for cobalt was greater than iron.The results suggest that the absorption of cobalt and iron is mediated by a transport system in which two processes operate simultaneously; the first is limited largely by the concentration of available metal in the lumen of the intestine, whereas the second process depends upon the activity of a mechanism which displays saturation kinetics and competitive inhibition. The former process prevails when iron stores are replete, whereas the latter predominates when there is a need for iron, such as in iron deficiency. INTRODUCTIONThe absorption of both iron and cobalt is increased in man and in the rat with iron deficiency (1-3). The predominant site of absorption of both elements in the rat is the proximal intestine, and the absorption of iron is proportional to the absorption of cobalt (3). The addition of cobalt to increasing concentrations of iron inhibits the transfer of iron from the lumen to the carcass (4, 5). Furthermore, the administration of iron with an oral dose of cobalt reduces cobalt transfer (6). These features suggest that iron and cobalt share at least part of a common absorptive pathway.The aim of this investigation was (a) to define the absorption kinetics for iron and cobalt; (b) to investigate the nature of the inhibitory effect of one metal upon the absorption of the other; and (c) to study the effect of varying body iron stores on these processes.The term transfer, when used in the text, is synonymous with absorption. METHODS Animals and diets. Iron deficiency was induced in one group of pathogen-free albino rats by raising them from weaning on a semisynthetic diet containing 10 mg/kg of iron (3,7,8 (5); the outflow tubing was set 15 cm above the loop to maintain uniform pressure. Following the perfusion period, the duo...

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Section: Effect Of Administering Iron and Cobalt Togethersupporting

confidence: 77%

mentioning

confidence: 99%

Competitive nature of the intestinal transport mechanism for cobalt and iron in the rat

Thomson¹,

Valberg²,

Sinclair³

1971

J. Clin. Invest.

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“…In contrast to iron-deficient animals, however, when the test dose of iron exceeded 50 ,Mg, the kinetics of the absorptive mechanism changed to those consistent with passive diffusion. We interpret this change to mean that the regulating effect of a limited mucosal transport and storage capacity for iron ("mucosal block") was exceeded to (17), in studies of over-all iron absorption in mice, found a change from a nonlinear to a linear relationship when doses greater than approximately 100 ug of iron were given. Their interpretation of the significance of this change is similar to ours, i.e., when a critical amount of iron is exceeded, a change in the predominant mechanism of absorption occurs.…”

Section: Methodsmentioning

confidence: 95%

Studies on Iron Absorption. Intestinal Regulatory Mechanisms*

Wheby¹,

Jones²,

Crosby³

1964

J. Clin. Invest.

161

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“…1). Further studies are necessary to clarify whether small amounts of ferrous iron are absorbed by an active, carrier-mediated process and therapeutic doses by diffusion, as inferred from experiments in mice [5]. Other theoretical aspects of ferrous iron absorption in fasting subjects, summarized under the term 'mucosal feed back regulation' have been discussed previously [8].…”

Section: Discussionmentioning

confidence: 99%

Interrelations between Diagnostic Criteria of the Iron Status and 50-mg Ferrous Iron Absorption in Iron-Replete and Iron-Deficient Subjects

Hausmann¹,

Kuse²,

Meinecke³

et al. 1973

Acta Haematol

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In comparison to other criteria of iron status, higher degrees of association have been computed between the diffuse Prussian blue reaction of the bone marrow macrophages and intestinal ferrous iron absorption, when test doses of 0.56 mg, 50 mg in solution, and 50 mg in quick-release capsules were given to fasting iron-replete controls and iron-deficient subjects in ⁵⁹Fe absorption whole-body retention tests. The variability of the results increased with rise of the test doses. Antecedent oral iron substitution and unallowed intake of food depressed ferrous iron absorption considerably.

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On the Kinetics of Iron Absorption in Mice*

Cited by 46 publications

References 10 publications

Competitive nature of the intestinal transport mechanism for cobalt and iron in the rat

Competitive nature of the intestinal transport mechanism for cobalt and iron in the rat

Studies on Iron Absorption. Intestinal Regulatory Mechanisms*

Interrelations between Diagnostic Criteria of the Iron Status and 50-mg Ferrous Iron Absorption in Iron-Replete and Iron-Deficient Subjects

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