Document Detail


The uptake of silicic acid by rat liver mitochondria.
MedLine Citation:
PMID:  28729     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
1. To gain insight into a putative role for mitochondria in silicon metabolism, mitochondrial uptake (by which it is meant the removal from the medium) of silicic acid [Si(OH)4] was studied under conditions minimizing SI(OH)4 polymerization. 2. Measurements of mitochondrial respiration and swelling indicated indirectly a significant uptake of Si(OH)4 as a weak acid, but this was not confirmed when 31Si(OH)4 was used as a tracer. 31Si(OH)4 occupied a mitochondrial volume similar to that of 3H2O and was relatively unaffected by mitochondrial energy status and by the pH gradient across the mitochondrial inner membrane. 3. Uptake was directly proportional to Si(OH)4 concentration in the range 0-3 mM. 4. The uptake consisted of two components: under all conditions examined, the greater quantity, amounting to 1-2nmol of Si(OH)4/mg of mitochondrial protein, was bound, a major portion of it external to the inner membrane, with the lesser quantity free within the matrix space. 5. Equilibration of 31Si(OH)4 between medium and matrix was a slow process, having a half-time of approx. 10 min at 22 degrees C. 6. Mersalyl and N-ethylmaleimide inhibited the uptake by preferentially lowering the amount of Si(OH)4 bound. Their action was somewhat variable, depending on the precise nature of the suspending medium, and suggesting that the bound material may represent polymerized forms of Si(OH)4. 7. It is concluded that Si(OH)4 may penetrate the mitochondrial inner membrane by a simple diffusion mechanism.
Authors:
R N Johnson; B E Volcani
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Biochemical journal     Volume:  172     ISSN:  0264-6021     ISO Abbreviation:  Biochem. J.     Publication Date:  1978 Jun 
Date Detail:
Created Date:  1978-10-25     Completed Date:  1978-10-25     Revised Date:  2010-08-31    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  557-68     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Hydrogen-Ion Concentration
Membranes / drug effects,  metabolism
Mitochondria, Liver / metabolism*
Rats
Silicic Acid / metabolism*,  pharmacology
Silicon Dioxide / metabolism*
Chemical
Reg. No./Substance:
1343-98-2/Silicic Acid; 7631-86-9/Silicon Dioxide
Comments/Corrections

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