Effects of acute, heavy-resistance exercise on urinary peptide hormone excretion in humans

IF(2007): 1.741To examine physical exerciserelated changes in urinary excretion of protein/peptide hormones and to correlate modifications with the general increase in postexercise proteinuria, urine Cpeptide, insulin and insulinlike growth factorI (IGFI) and their plasma concentrations were measured. Plasma and urinary Cpeptide, insulin and IGFI before (B-ex) and at the end (E-ex) of physical exercise (a 2.5-hour competition, 102 km) were analysed in 20 young cyclists. At Eex compared with Bex, concentration of urinary Cpeptide decreased slightly but significantly (21.3 +/- 2.7 vs. 13.5 +/- 1.7 nmol/l), but urinary insulin and urinary IGFI concentrations significantly increased at Eex (92.5 +/- 4.2 vs. 131.4 +/- 15.7 pmol/l and 10.0 +/- 2.1 vs. 33.6 +/- 3.8 pmol/l, respectively). Plasma insulin and plasma C-peptide significantly decreased, whereas plasma IGFI was unchanged. Urinary concentrations of total proteins and creatinine significantly increased. Both E-ex urinary C-peptide/urinary protein and urinary C-peptide/urinary creatinine ratios were significantly reduced. The correlation between C-peptide and insulin in plasma was confirmed at Bex as well as E-ex, but in urine only at Bex. An increased renal tubular reabsorption of C-peptide at the end of exercise might be suggested, but the expected values considering creatinine excretion were almost three times less. The E-ex urinary insulin concentration was higher than expected, considering the circulation levels, but lower when compared with the expected concentration considering creatinine excretion. Physical exercise proteinuria, related to an increased protein filtration and a saturation of the mechanisms responsible for the reabsorption, does not appear similar for all peptide hormones