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The effect of serum iron concentration on iron secretion into mouse milk
Author(s) -
Zhang Peifang,
Sawicki Valerie,
Lewis Andy,
Hanson Linda,
Monks Jenifer,
Neville Margaret C.
Publication year - 2000
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2000.t01-2-00479.x
Subject(s) - transferrin , lactoferrin , transferrin receptor , basal (medicine) , endocrinology , medicine , lactation , secretion , chemistry , mammary gland , receptor , serum iron , biology , biochemistry , pregnancy , hemoglobin , genetics , cancer , breast cancer , insulin
The concentration of iron in mouse milk is approximately 3 times that of the serum. Although there is clear evidence for the presence of the transferrin receptor in the rodent mammary gland, the precise mechanisms of iron transfer into milk are not known. Milk iron was linearly related to the serum iron:transferrin ratio in lactating mice whose serum iron ranged from 8 to 66 μ m . Increasing the iron binding capacity of the milk by 340 μ m by targeting the lactoferrin transgene to the mammary gland did not alter the relation between milk iron and the serum iron:transferrin ratio. The steady‐state distribution ratio of 125 I‐transferrin between plasma and milk was about 0.2, indicating that transcytosed transferrin contributed a maximum of 6% of the milk iron. Fluorescently labelled transferrin incubated with the in situ gland localized mainly near the basal surface of the mammary alveolar cells. These experiments provide evidence that the initial and rate‐limiting step in the transfer of iron into milk is binding to a basal transferrin receptor. A theoretical model of the relation between milk and serum iron suggests that the affinity of apotransferrin for the basal recycling system may be higher than observed in many other cell types.