Increased renal tubular sodium reabsorption during exercise-induced hypervolemia in humans

Kei Nagashima, Jauchia Wu, Stavros A. Kavouras, Gary W. Mack*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


We tested the hypothesis that renal tubular Na+ reabsorption increased during the first 24 h of exercise-induced plasma volume expansion. Renal function was assessed 1 day after no-exercise control (C) or intermittent cycle ergometer exercise (Ex, 85% of peak O2 uptake) for 2 h before and 3 h after saline loading (12.5 ml/kg over 30 min) in seven subjects. Ex reduced renal blood flow (p-aminohippurate clearance) compared with C (0.83 ± 0.12 vs. 1.49 ± 0.24 l/min, P < 0.05) but did not influence glomerular filtration rates (97 ± 10 ml/min, inulin clearance). Fractional tubular reabsorption of Na+ in the proximal tubules was higher in Ex than in C (P < 0.05). Saline loading decreased fractional tubular reabsorption of Na+ from 99.1 ± 0.1 to 98.7 ± 0.1% (P < 0.05) in C but not in Ex (99.3 ± 0.1 to 99.4 ± 0.1%). Saline loading reduced plasma renin activity and plasma arginine vasopressin levels in C and Ex, although the magnitude of decrease was greater in C (P < 0.05). These results indicate that, during the acute phase of exercise-induced plasma volume expansion, increased tubular Na+ reabsorption is directed primarily to the proximal tubules and is associated with a decrease in renal blood flow. In addition, saline infusion caused a smaller reduction in fluid-regulating hormones in Ex. The attenuated volume-regulatory response acts to preserve distal tubular Na+ reabsorption during saline infusion 24 h after exercise.

Original languageEnglish
Pages (from-to)1229-1236
Number of pages8
JournalJournal of Applied Physiology
Issue number3
Publication statusPublished - 2001
Externally publishedYes


  • Colloid osmotic pressure
  • Lithium clearance
  • Renal blood flow
  • Renal function

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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