EVIDENCE OF DIFFERENTIAL RENAL DYSFUNCTIONS DURING EXERCISE IN MEN

Post-exercise proteinuria is a common phenomenon in healthy subjects. Previous studies have used albumin (Alb) and beta(2)-microglobulin (be ta(2)-m) molecules as representatives of high- and low-molecular-weigh t proteins. Recently, more specific markers of the human kidney proxim al tubule have been used to identify the precise site of alterations. Active male subjects underwent two strenuous runs, one 400-m run and o ne 3000-m run. Urine was collected from the subjects before and after each event. Total protein (TP), Alb, alpha(1)-microglobulin (alpha(1)- m), beta(2)-m, intestinal alkaline phosphatase (IAP), tissue-nonspecif ic alkaline phosphatase (TNAP) and N-acetyl-beta-D-glucosaminidase (NA G) were determined for each sample. The short-distance run (400 m) res ulted in the largest increases (P less than or equal to 0.05) in TP (3 1-fold), Alb (100-fold) and beta(2)-m (164-fold) as compared to the lo ng-distance run (3000-m). The alpha(1)-m excretion rates were increase d to a lesser extent by the exercises. The IAP activity was slightly i ncreased (+90%) by the 400-m run while the TNAP and NAG activities sho wed a 6.8-fold and a 3.6-fold increase, respectively, after this event . Smaller increases were recorded for the long-distance run (P = 0.05) . To conclude, the present investigation showed that: (1) post-exercis e proteinuria is related to the absolute intensity of exercise; (2) th e impairment of protein reabsorption is revealed better by changes in Alb and beta(2)-m; (3) changes in TNAP and NAG activities could reveal biochemical modifications that occur in the proximal tubule, particul arly at the S1-S2 segment.