Indirect evidence of glomerular/tubular mixed-type postexercise proteinuria in healthy humans

Abstract

Hypothetical mechanisms have been postulated to explain the presence of proteins in urine after severe exercise. Recently, it has been shown that several amino acids inhibit tubular protein reabsorption. Seven healthy men, hyperhydrated, were studied during a 2-min bicycle exercise at supramaximal load. The subjects were tested without or with lysine perfusion (0.4 g/kg body wt iv). In both testing conditions, blood lactate increased to 13.8 mmol/l. Total protein urinary excretion increased to 1.10 and 1.67 mg/min, without and with lysine perfusion, compared with 79 micrograms/min at rest. In the meantime, albumin excretion increased 48- and 74-fold, respectively, while beta 2-microglobulin excretion increased 97- and 1,043-fold compared with basal values. The renal clearance of albumin increased to 8.4 microliters/min without lysine and to 12.0 microliters/min with lysine perfusion (rest 0.18). beta 2-Microglobulin clearance increased to 10.0 and 39.3 ml/min, respectively (rest 0.05). These data clearly demonstrate that postexercise proteinuria is of mixed type after exhaustive short-term exertion. Both increased glomerular permeability and partial tubular reabsorption inhibition to proteins appear to be involved.

Glomerular Filtration Rate and Albumin Excretion After Maximal Exercise in Aging Sedentary and Active Men

“…It is useful to assess indirectly changes in glomerular membrane permeability by measuring the urine excretion rate of plasma albumin. We have provided evidence of an enhanced glomerular permeability induced by short-term strenuous exercise in young adults (8). It also appeared that postexercise proteinuria was more related to the intensity of the exercise (power output) than to its relative intensity (% of VO 2max ) (7).…”

“…Postexercise proteinuria is more specifically related to the intensity than to the duration of the exercise (7). Moreover, the excretion of plasma proteins is due primarily to enhanced glomerular membrane permeability associated with a saturation of the reabsorption process (8). These effects, which are intensity-dependent, are transient, with return to basal state with a half-life of about 1 hour (9).…”

Rust Urine after Intense Hand Drumming Is Caused by Extracorpuscular Hemolysis

“…The mechanisms postulated for glomerular proteinuria are changes in glomerular hemodynamics and in basal glomerular membrane permeability (13)(14)(15). Proteinuria disappeared after drumming in all of the individuals with RU.…”

Increased Urinary Transferrin Excretion in Exercising Normoalbuminuric Insulin-Dependent Diabetic Patients

“…however, found that there was a pattern of proteinuria suggestive of mixed glomerulo-tubular loss during an exercise test in diabetic subjects given lysine, an amino acid which blocks tubular reabsorption of filtered protein. 13 Our finding of increased albumin and transferrin excretion following exercise in the diabetic group is evidence for a glomerular leak.…”