The influence of high iron diet on rat lung manganese absorption.
Individuals chronically exposed to manganese are at high risk for neurotoxic effects of this metal. A primary route of exposure is through respiration, although little is known about pulmonary uptake of metals or factors that modify this process. High dietary iron levels inversely affect intestinal uptake of manganese, and a major goal of this study was to determine if dietary iron loading could increase lung non-heme iron levels and alter manganese absorption. Rats were fed a high iron (1% carbonyl iron) or control diet for 4 weeks. Lung non-heme iron levels increased approximately 2-fold in rats fed the high iron diet. To determine if iron-loading affected manganese uptake, 54Mn was administered by intratracheal (it) instillation or intravenous (iv) injection for pharmacokinetic studies. 54Mn absorption from the lungs to the blood was lower in it-instilled rats fed the 1% carbonyl iron diet. Pharmacokinetics of iv-injected 54Mn revealed that the isotope was cleared more rapidly from the blood of iron-loaded rats. In situ analysis of divalent metal transporter-1 (DMT1) expression in lung detected mRNA in airway epithelium and bronchus-associated lymphatic tissue (BALT). Staining of the latter was significantly reduced in rats fed the high iron diet. In situ analysis of transferrin receptor (TfR) mRNA showed staining in BALT alone. These data demonstrate that manganese absorption from the lungs to the blood can be modified by iron status and the route of administration.
Thompson
Khristy
K
Department of Genetics and Complex Diseases, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115, USA.
Molina
Ramon
R
Donaghey
Thomas
T
Brain
Joseph D
JD
Wessling-Resnick
Marianne
M
D000042:Absorption; D000818:Animals; D027682:Cation Transport Proteins / Q000096:biosynthesis; D006400:Hematocrit; D017403:In Situ Hybridization; D007275:Injections, Intravenous; D007322:Instillation, Drug; D007442:Intubation, Intratracheal; D054354:Iron Carbonyl Compounds; D019266:Iron, Dietary / Q000008:administration & dosage / Q000494:pharmacology*; D033862:Iron-Binding Proteins / Q000096:biosynthesis; D008168:Lung / Q000187:drug effects* / Q000378:metabolism; D008221:Lymphoid Tissue / Q000187:drug effects / Q000378:metabolism; D008297:Male; D017895:Manganese Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics*; D019159:Nonheme Iron Proteins / Q000378:metabolism; D009942:Organometallic Compounds / Q000008:administration & dosage / Q000494:pharmacology; D011868:Radioisotopes; D051381:Rats; D017207:Rats, Sprague-Dawley; D011990:Receptors, Transferrin / Q000096:biosynthesis; D020545:Respiratory Mucosa / Q000187:drug effects / Q000378:metabolism; D000099236:Solute Carrier Family 11, Member 2
D027682:Cation Transport Proteins; D054354:Iron Carbonyl Compounds; D019266:Iron, Dietary; D033862:Iron-Binding Proteins; D017895:Manganese Compounds; D019159:Nonheme Iron Proteins; D009942:Organometallic Compounds; D011868:Radioisotopes; D011990:Receptors, Transferrin; D000099236:Solute Carrier Family 11, Member 2