Document Detail

Metabolic requirement for inorganic phosphate by the rabbit proximal tubule.
MedLine Citation:
PMID:  7085888     Owner:  NLM     Status:  MEDLINE    
These studies examine the effects of acute changes in the availability of inorganic phosphate on the function of isolated proximal renal tubules from rabbit kidney. We removed phosphate from the extracellular fluids and measured fluid absorption rates in isolated perfused tubules and oxygen consumption rates in suspensions of cortical tubules. In proximal convoluted tubules, the selective removal of phosphate from the luminal fluid reduced fluid absorption rates from 1.11+/-0.12 to -0.01+/-0.08 nl/mm . min. This effect on fluid absorption was dependent on the presence of glucose transport and metabolism. The addition of phlorizin to the phosphate-free luminal fluid preserved fluid absorption rates (1.12+/-0.12 nl/mm . min) as did the substitution of nonmetabolized alpha-methyl d-glucopyranoside for glucose (1.05+/-0.21 nl/mm . min) or the addition of 2-deoxyglucose, an inhibitor of glycolysis, to the bathing medium (1.01+/-0.15 nl/mm . min). There was no effect on fluid absorption if phosphate was removed from the bath only. Additionally, removal of phosphate from the luminal fluid of proximal straight rather than convoluted tubules had no effect on fluid absorption rates. Oxygen consumption rates in suspensions of cortical tubules were reduced from 18.9+/-0.6 to 10.6+/-0.6 nmol O(2)/mg tubular protein . min by the removal of phosphate from the medium. This inhibition was prevented by the substitution of alpha-methyl d-glucopyranoside for glucose in the phosphate-free medium. The data indicate that under certain conditions, proximal convoluted tubules require the presence of phosphate in the luminal fluid to preserve tubular function. In the absence of intraluminal phosphate, glucose metabolism causes a reduction in both oxidative metabolism and fluid absorption. This response is analogous to the Crabtree effect and suggests limitations on the intracellular availability of inorganic phosphate.
P C Brazy; S R Gullans; L J Mandel; V W Dennis
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of clinical investigation     Volume:  70     ISSN:  0021-9738     ISO Abbreviation:  J. Clin. Invest.     Publication Date:  1982 Jul 
Date Detail:
Created Date:  1982-08-14     Completed Date:  1982-08-14     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  7802877     Medline TA:  J Clin Invest     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  53-62     Citation Subset:  AIM; IM    
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MeSH Terms
Biological Transport
Glucose / metabolism
Kidney Tubules, Proximal / metabolism*
Methylglucosides / metabolism
Mitochondria / metabolism
Nystatin / pharmacology
Oxygen Consumption
Phosphates / metabolism*
Sodium / metabolism
Grant Support
Reg. No./Substance:
0/Methylglucosides; 0/Phosphates; 1400-61-9/Nystatin; 50-99-7/Glucose; 7440-23-5/Sodium

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