Effect of age on dopaminergic responses to protein feeding

Naomi K. Fukagawa*, Linda G. Bandini, Mary Ann Lee, James B. Young

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Renal excretory responses to protein feeding were compared in nine young (20-26 yr) and nine elderly (70-89 yr) men. Although protein increased excretion of dopamine and serotonin (5-HT, P < 0.001 for both), the basal excretion of dopamine and 5-HT was less in old than young men (P < 0.05). Protein increased sodium and water excretion in the young; responses in elderly for both were less (P < 0.025). Carbidopa markedly suppressed dopamine and 5-HT excretion in both young and old men. Carbidopa also attenuated protein-induced natriuresis and diuresis and raised serum aldosterone levels in the young but not in the old men. These age-related differences in dopamine and 5-HT excretion were not abolished by alterations in dietary NaCl. Thus, although dopamine excretion is decreased overall in elderly men, sodium and water excretion and aldosterone secretion in the old men were unaffected by alterations in dopamine production. These data suggest that impaired protein-induced natriuresis in the old men may be due to limitations in renovascular responses and that, in young men, dopamine and 5- HT may contribute to the protein-induced changes in renovascular function.

Original languageEnglish (US)
Pages (from-to)F613-F625
JournalAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Issue number4 37-4
StatePublished - 1995


  • L-aromatic amino acid decarboxylase
  • aldosterone
  • carbidopa
  • creatinine clearance
  • dietary sodium
  • dihydroxyphenylalanine
  • dopamine
  • renal blood flow
  • serotonin
  • sodium excretion

ASJC Scopus subject areas

  • Physiology


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