EXERCISE INDUCED SODIUM CONSERVATION - CHANGES IN PLASMA-RENIN AND ALDOSTERONE

  • 1 January 1976
    • journal article
    • research article
    • Vol. 8  (4) , 209-213
Abstract
Previous studies demonstrated a renal Na+ conservation during repeated days of exercise in the heat. The present study was intended to describe the role of [human] plasma aldosterone (PAC) in reducing urine Na+ losses during and after 60 min of exercise (60% .ovrhdot.VO2 max [maximal aerobic power]) in a warm environment (30.degree. C, 50-53% relative humidity). Additional measurements were made of plasma renin activity (PRA) in an effort to demonstrate the relationship between PRA and PAC. A single bout of exercise can significantly reduce urine Na+, Cl- and H2O excretion for up to 48 h. Both PRA and PAC were significantly elevated during and immediately after exercise and returned to the pre-exercise level within 6-12 h of recovery. Subsequently, ingestion of 180 meq of Na+ each day with ad lib water intake results in an increased NaCl storage and an expansion of the extracellular volume.