Document Detail

Protein-induced increase in urinary dopamine in normal and diabetic rats: role of catecholamine precursors.
MedLine Citation:
PMID:  9249535     Owner:  NLM     Status:  MEDLINE    
Feeding and protein intake increase renal dopamine excretion (UDAV). Here the contribution of amino acids (AA), L-tyrosine (Tyr), and L-phenylalanine (Phe) to UDAV in conscious normal rats and in animals with streptozotocin (STZ)-induced (60 mg/kg) diabetes mellitus was investigated. Feeding a standard chow (17.3% protein) increased UDAV in normal rats over twofold compared with the fasted state, but the effect was completely abolished by feeding a low-protein (LP, 0.03%) diet. In STZ rats, UDAV was equal to that of normal rats during the fasted periods but was higher in fed animals, resulting most likely from the higher protein intake of STZ rats. In another series, rats on LP diet were given AA solutions (7, 14, and 21 h-1) by gastric tube, which dose dependently increased UDAV to 67.3 +/- 4.3, 91.1 +/- 5.0, and 129 +/- 17, respectively, compared with tap water as vehicle control (H2O, 55.6 +/- 7.0 In rats kept without access to chow, administration of AA including Phe and Tyr (AAPT) increased UDAV twofold compared with H2O, whereas AA solution without Tyr and Phe did not change UDAV. Tyr or Phe alone increased UDAV to the same extent as observed in AAPT. Higher doses of Tyr further increased UDAV dose dependently but with saturation characteristics. UDAV of the animals that were in a slightly negative sodium balance was not correlated to renal sodium excretion. It is concluded that, in conscious rats, the increase in UDAV in response to feeding 1) depends on the supply of catecholamine precursors solely, 2) is dose dependent and saturable, and 3) is not affected by experimental diabetes mellitus.
B Mühlbauer; C Mickeler; F Schenk
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of physiology     Volume:  273     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1997 Jul 
Date Detail:
Created Date:  1997-09-03     Completed Date:  1997-09-03     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  R80-5     Citation Subset:  IM    
Institute of Pharmacology, University of Tübingen, Germany.
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MeSH Terms
Animal Feed
Diabetes Mellitus, Experimental / physiopathology*,  urine
Diet, Protein-Restricted*
Dietary Proteins*
Dopamine / urine*
Phenylalanine / administration & dosage,  pharmacology
Rats, Sprague-Dawley
Tyrosine / administration & dosage,  pharmacology
Reg. No./Substance:
0/Dietary Proteins; 55520-40-6/Tyrosine; 63-91-2/Phenylalanine

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