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  1. Article: Manganese and iron transport across pulmonary epithelium.

    Heilig, Elizabeth A / Thompson, Khristy J / Molina, Ramon M / Ivanov, Alexander R / Brain, Joseph D / Wessling-Resnick, Marianne

    American journal of physiology. Lung cellular and molecular physiology

    2006  Volume 290, Issue 6, Page(s) L1247–59

    Abstract: ... demonstrate that iron and manganese are absorbed by the pulmonary epithelium through different pathways and ... Pathways mediating pulmonary metal uptake remain unknown. Because absorption of iron and manganese ... examined. Tf mRNA was detected in bronchial epithelium, type II alveolar cells, macrophages, and bronchus ...

    Abstract Pathways mediating pulmonary metal uptake remain unknown. Because absorption of iron and manganese could involve similar mechanisms, transferrin (Tf) and transferrin receptor (TfR) expression in rat lungs was examined. Tf mRNA was detected in bronchial epithelium, type II alveolar cells, macrophages, and bronchus-associated lymphoid tissue (BALT). Tf protein levels in lung and bronchoalveolar lavage fluid did not change in iron deficiency despite increased plasma levels, suggesting that lung Tf concentrations are regulated by local synthesis in a manner independent of body iron status. Iron oxide exposure upregulated Tf mRNA in bronchial and alveolar epithelium, macrophages, and BALT, but protein was not significantly increased. In contrast, TfR mRNA and protein were both upregulated by iron deficiency. To examine potential interactions with lung Tf, rats were intratracheally instilled with (54)Mn or (59)Fe. Unlike (59)Fe, interactions between (54)Mn and Tf in lung fluid were not detected. Absorption of intratracheally instilled (54)Mn from the lungs to the blood was unimpaired in Belgrade rats homozygous for the functionally defective G185R allele of divalent metal transporter-1, indicating that this transporter is also not involved in pulmonary manganese absorption. Pharmacological studies of (54)Mn uptake by A549 cells suggest that metal uptake by type II alveolar epithelial cells is associated with activities of both L-type Ca(2+) channels and TRPM7, a member of the transient receptor potential melastatin subfamily. These results demonstrate that iron and manganese are absorbed by the pulmonary epithelium through different pathways and reveal the potential role for nonselective calcium channels in lung metal clearance.
    MeSH term(s) Animals ; Base Sequence ; Biological Transport ; DNA Primers ; In Situ Hybridization ; Iron/metabolism ; Lung/cytology ; Lung/physiology ; Male ; Manganese/metabolism ; RNA, Messenger/genetics ; Rats ; Rats, Sprague-Dawley ; Receptors, Transferrin/genetics ; Respiratory Mucosa/cytology ; Respiratory Mucosa/physiology ; Transferrin/genetics
    Chemical Substances DNA Primers ; RNA, Messenger ; Receptors, Transferrin ; Transferrin ; Manganese (42Z2K6ZL8P) ; Iron (E1UOL152H7)
    Language English
    Publishing date 2006-01-20
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 1013184-x
    ISSN 1522-1504 ; 1040-0605
    ISSN (online) 1522-1504
    ISSN 1040-0605
    DOI 10.1152/ajplung.00450.2005
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Homeostatic and toxic mechanisms regulating manganese uptake, retention, and elimination

    JEROME A ROTH

    Biological Research, Vol 39, Iss 1, Pp 45-

    2006  Volume 57

    Abstract: ... in the nasal mucosa and the subsequent retrograde axonal transport directly into the CNS; 2) transport across ... the pulmonary epithelial lining and its subsequent deposition into lymph or blood; and/or 3) mucocilliary ... as a description of the various mechanisms that have been proposed for the transport of Mn across ...

    Abstract This review attempts to summarize and clarify our basic knowledge as to the various factors that potentially influence the risks imposed from chronic exposure to high atmospheric levels of manganese (Mn). The studies describe the interrelationship of the different systems in the body that regulate Mn homeostasis by characterizing specific, biological components involved in its systemic and cellular uptake and its elimination from the body. A syndrome known as manganism occurs when individuals are exposed chronically to high levels of Mn, consisting of reduced response speed, intellectual deficits, mood changes, and compulsive behaviors in the initial stages of the disorder to more prominent and irreversible extrapyramidal dysfunction resembling Parkinson's disease upon protracted exposure. Mn intoxication is most often associated with occupations in which abnormally high atmospheric concentrations prevail, such as in welding and mining. There are three potentially important routes by which Mn in inspired air can gain access the body to: 1) direct uptake into the CNS via uptake into the olfactory or trigeminal presynaptic nerve endings located in the nasal mucosa and the subsequent retrograde axonal transport directly into the CNS; 2) transport across the pulmonary epithelial lining and its subsequent deposition into lymph or blood; and/or 3) mucocilliary elevator clearance from the lung and the subsequent ingestion of the metal in the gastrointestinal tract. Each of these processes and their overall contribution to the uptake of Mn in the body is discussed in this review as well as a description of the various mechanisms that have been proposed for the transport of Mn across the blood-brain barrier which include both a transferrin-dependent and a transferrin-independent process that may involve store-operated Ca channels.
    Keywords manganese ; iron ; lung ; Parkinson's disease ; divalent metal transporter (DMT1) ; transferrin ; transferrin receptor ; Biology (General) ; QH301-705.5
    Subject code 610
    Language English
    Publishing date 2006-01-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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