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In vivo characterization of renal iron transport in the anaesthetized rat
Author(s) -
Wareing Mark,
Ferguson Carole J.,
Green Roger,
Riccardi Daniela,
Smith Craig P.
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.1469-7793.2000.00581.x
Subject(s) - microinjection , reabsorption , chemistry , in vivo , zinc , manganese , distal convoluted tubule , kidney , endocrinology , tubular fluid , medicine , biology , microbiology and biotechnology , organic chemistry
1 In vivo microinjections of 55 FeCl 3 were made to assess renal iron (Fe 2+/3+ ) transport in the anaesthetized rat. 2 Following microinjection into proximal convoluted tubules (PCTs), 18·5 ± 2·9 % (mean ± s.e.m., n = 11) of the 55 Fe was recovered in the urine. This recovery was not dependent on the injection site indicating that iron is not reabsorbed across the surface convolutions of the proximal tubule. 3 Following microinjection into distal convoluted tubules (DCTs) 46·1 ± 6·1 % ( n = 8 ) of the injected 55 Fe was recovered. Taken together the recovery data from the PCT and DCT microinjection studies indicate that the transport of iron occurs in the loop of Henle (LH) and collecting duct system. 4 In vivo luminal microperfusion was used to examine iron transport by the LH in more detail. In tubules perfused with 7 μmol l −1 55 FeCl 3 , 52·7 ± 8·3 % ( n = 8 ) of the perfused 55 Fe was recovered in the collected fluid, indicating significant iron reabsorption in the LH. Addition of copper (Cu 2+ as 7 μmol l −1 CuSO 4 ), manganese (Mn 2+ as 7 μmol l −1 MnSO 4 ) or zinc (Zn 2+ as 7 μmol l −1 ZnSO 4 ) to the perfusate did not affect reabsorption of water, Na + or K + , but increased recovery of 55 Fe to 83·5 ± 6·8 % ( n = 8, P < 0·04), 75·8 ± 5·9 ( n = 6, not significant, n.s.) and 67·9 ± 3·8; ( n = 9, n.s.), respectively. 5 Thus, iron transport in the LH can be reduced by the addition of copper or manganese to the luminal perfusate suggesting that these ions may compete with iron for a common transport pathway. However, this pathway may not be shared by zinc.