Urinary excretion of immunoglobulins and their subunits in human subjects before and after exercise

Immunoglobulins and their subunits in urines collected before and after exercise from healthy human subjects were studied. Quantitative analysis showed that only gamma A- and gamma G-immunoglobulins were excreted as whole molecules in normal urine, at a concentration of 0.35 and 1.70 micrograms/min., respectively. Exercise enhanced the excretion of both types of molecules. In some cases, gamma D-immunoglobulins were found in "exercise urine." Gel filtration on Sephadex G-150 showed that only gamma G-subunits were present in normal and in "exercise urine." The distribution of gamma G-subunits was not affected by exercise. The authors consider the importance of the present data in relation to renal physiology.

Urine protein excretion and swimming events

To determine total urinary protein, albumin (ALB), and beta 2-microglobulin (beta 2m) excretion rates in relation to different speeds, 12 males were studied while swimming distances of 100, 600, and 2,000 m at maximal speed. Venous blood lactate concentrations rose to 16.1, 11.6, and 4.5 mmol.l-1 after the 100, 600, and 2,000 m events, while plasma volumes were reduced by 11.3, 7.7, and 5.5%, respectively. ALB urine excretion increased to 110-120 micrograms.min-1 after the 100 and 600 m swims and to 56 micrograms.min-1 after 2,000 m (resting values: 9 micrograms.min-1). In the meantime, the beta 2m excretion rate increased 21 and 10 times the resting values, respectively, for the two shorter swims, with no change for the longer one. Progressive plasma volume reduction was associated with the increase of the protein excretion rate. As evidenced by the creatinine clearance, the glomerular filtration rate did not change for the 100 m swim but dropped by 23 and 35% for the 600 and 2,000 m ones, respectively. On the other hand, the ALB clearance increases were elevated for the three swims, while the beta 2m clearance increases were inversely related to the swimming speeds. The data showed a relationship between the rate of protein excretion and the speed of the swim, and the reduction of plasma volume. The findings could indicate a renal glomerular alteration, with an additional dysfunction of the tubular reabsorption process when the exercise load is high during swimming events.

Decreased plasma tryptophan concentration in major depression: relationship to melancholia and weight loss

Plasma total tryptophan (TRP) concentration was significantly lower in 31 patients with major depression compared to a healthy control group. The ratio of plasma TRP concentration to that of other branch chain amino acids (the TRP:BCAA ratio) was also decreased. Further analysis revealed that the decrease in plasma TRP and TRP:BCAA ratio was most apparent in patients with major depression and melancholia. Overall, women but not men had significantly decreased plasma tryptophan concentrations, perhaps because of a contributory effect of weight loss; this latter effect, however, could not be distinguished clearly from a diagnosis of melancholia. Our data suggest that in some depressed patients, reductions in plasma tryptophan availability may contribute to abnormalities in brain 5-hydroxytryptamine function.

Postexercise proteinuria in rowers

Exercise performance, glomerular filtration rate (GFR), and urinary filtration of proteins during static pool rowing and cycling to exhaustion were studied in trained rowers. The peak VO2 and heart rate were higher during rowing than during cycling. There was a reduction in plasma volume and an increase in lactate concentration after exercise; however, no significant difference was noted between rowing and cycling in either case. Postexercise proteinuria was increased 8 and 11 times, and albuminuria 25 and 20 times after rowing and cycling exercises, respectively. There was no difference between these exercises in terms of protein or albumin excretion. There was no change in postexercise GFR. Albumin clearance was increased 18 and 20 fold after rowing and cycling, respectively. A significant, but low correlation, r = 0.56, was noted between albumin excretion and postexercise blood lactate concentration. Thus, no difference in the effect on kidney response was found between static pool rowing and cycling to exhaustion in these athletes.

The influence of air-cushion shoes on post-exercise proteinuria

Fourteen trained males participated in three sets of progressive 1 min exercise till exhaustion comparing proteinuria after bicycling, treadmill running under barefoot and air-cushion shoe conditions. Venous lactate rose to about 11 moles.l-1 after the three bouts of exercise while total protein and albumin urinary excretion increased 7 (rest micrograms.min-1) and 19 (rest 11 micrograms.min-1) fold respectively. Creatinine clearance declined to 75% (88 ml.min-1) of the resting values for all three exercises. Albumin clearances increased from 0.24 microliter.min-1 at rest to 4.08 microliters.min-1 during the recovery period. None of the above values were statistically different while comparing the three protocols. On the contrary, plasma hemoglobin showed a significant rise with bare-footed-running (rest 10 mg.100 ml-1; exercise 21 mg.100 ml-1). The lack of hemoglobin in urine postulated that the renal threshold for excretion was not attained in the present conditions. The results indicate that haemolysis and repeated shocks on the foot sole do not lead to the urinary excretion of proteins induced by short-term progressive and exhaustive exercise in humans.

Renal protein excretion after exercise in man

Thirteen men were submitted to graded exhaustive cycle exercise to determine the kinetics of proteinuria in the recovery period. Venous blood samples were analysed for haematocrit, lactate, creatinine, total protein and albumin for 1 h following exercise. Urine samples were collected during a 3-h recovery period. Total protein, albumin, and creatinine levels were determined for these samples. Total protein and albumin urinary excretion increased to 581 and 315 micrograms min-1, respectively, at the end of the 1st h of recovery as compared to 42 and 15 micrograms.min-1 for resting values. Plasma volume returned to pre-exercise levels between 30 and 60 min after cessation of exercise, while urinary total protein and albumin content still remained above the resting values for the following 2 h. Both post-exercise urinary total protein and albumin excretion followed a logarithmic decline with the same half-life of 54 min, thus requiring about 4 h to regain resting values. The reduction of plasma volume and the degree of dehydration do not seem to be involved in the process. The present study indicates the delayed recovery of protein handling by the kidney, as compared with other biochemical parameters, and provides accurate information on the kinetics of post-exercise proteinuria.

Effects of inactivity and exercise on bone

Bone mass and muscular mass show a parallel evolution during growth, and parallel involution with age. However, the bone loss related to the withdrawal of oestrogens is independent of muscular waste. The extensive study of disuse osteoporosis shows that exercise without weightbearing cannot counteract the loss of bone mass provoked by bed rest or weightlessness. Physical training, even at low frequency (30 to 60 min/day, 2 or 3 days/week), can increase bone mass or reduce bone loss associated with age. This effect is even present when exercise is practised by very old people at a seemingly low level of muscular tension on bone. It is not known whether muscular exercise could be helpful in pathological osteopenia. Experiments in animals indicate a short-lived benefit of exercise practised during a definite growth period; the long term effect of physical training in humans, after cessation of such activity, has not been studied extensively. Equal distribution of tension on all parts of the skeleton is probably not mandatory to obtain a general effect of exercise on bone mass. It is assumed that muscular exercise acts through tension exerted on bone, but the exact mechanism is unknown, as are the specifications of effective exercise in terms of site of application, intensity, frequency and duration. Moreover, little is known about the expected synergy between exercise and occupational activity.

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

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.

The influence of work intensity on postexercise proteinuria

Fifteen men were studied during 100 m, 400 m and 3,000 m runs at maximal speed to determine total urinary protein and albumin excretion rates in relation to different distances of running. Venous blood lactate rose to 7.5 mmol.l-1 after the 100 m and 3,000 m events, while reaching 12 mmol.l-1 after the 400 m dash. Total urinary protein excretion increased to 330, 1640 and 565 micrograms.min-1 after the 100 m, 400 m and 3,000 m runs respectively, as compared with basal values (70 micrograms.min-1). In the meantime, albumin excretion increased respectively by 5, 25 and 18 fold of the resting values. The renal clearance of albumin increased to 0.84, 5.62 and 3.35 microliter.min-1 after the three runs, as compared with a mean value of 0.19 microliter.min-1 at rest. Exponential relationships (r = 0.85) were recorded between post-exercise venous lactate and albumin, and total protein excretion. The present work illustrates the major influence of the intensity of exercise (anaerobic glycolytic component), rather than its duration, on the excretion rate of urinary proteins.

Influence of the degree of metabolic control on physical fitness in type I diabetic adolescents

Seventeen type I male diabetic adolescents and 17 control subjects matched for age, height, and weight were submitted to maximal exercise on a bicycle ergometer. The diabetic subjects were divided into two groups according to their degree of metabolic control using total glycosylated hemoglobin (HbA1): group 1, diabetics with HbA1 less than 8.5% (n = 9) and group 2, diabetics with HbA1 greater than 8.5% (n = 8). Oxygen uptake, pulmonary ventilation, and heart rate were recorded at rest and at maximal load. Glucose, lactate, and free fatty acids were determined in blood before and after exercise. Maximal work load and oxygen uptake were significantly lower in the two diabetic groups than in the healthy controls. An inverse relationship was observed between HbA1 concentration and the maximal work load (r = -0.63; P less than 0.01). It can be concluded that diabetic adolescents should obtain the best possible degree of metabolic control to improve their performances.

Metabolic implications during a 20-km run after heart transplantation

The aim of the present study was to evaluate a heart transplanted patient who ran a 20-km race 9 months after surgery. Thirty-six healthy male subjects were studied during the same run and served as control group. Biochemical variables were determined in blood and urine samples collected before and after the race. Post-exercise blood urea increased by 23% (P less than 0.05) in the control group but remained unchanged in the patient. Blood lactate increased far more in the transplanted patient (7.07 mmol/L) than in the control subjects (2.53 mmol/L). The exercise induced a 5.46- and 0.67-fold increase in creatine phosphokinase activity in the transplanted patient and control group, respectively. The creatinine and urea urinary excretion and clearance decreased by 40%-60% after exercise for all subjects. It may be concluded that the heart transplanted patient responded for most registered variables in the same way as normal subjects, but some differences occurred on the renal side due to the use of an immunosuppressive drug.

Postexercise proteinuria in humans. Facts and mechanisms

Strenuous exercise induces profound changes in renal hemodynamics and the protein content of urine. Postexercise proteinuria seems to be directly related to the intensity of exercise, rather than to its duration. The pattern of proteins identified in urine collected after exercise is different from normal physiological proteinuria. Immunochemical techniques demonstrate that postexercise proteinuria is of mixed glomerular-tubular type when heavy exercise is involved. The origin of proteinuria after light exercise seems to be preponderantly of glomerular type. Clearance of individual plasma proteins suggests an increased glomerular permeability and a partial tubular-reabsorption inhibition of macromolecules.

Exercise and renal function

Exercise induces profound changes in the renal haemodynamics and in electrolyte and protein excretion. Effective renal plasma flow is reduced during exercise. The reduction is related to the intensity of exercise and renal blood flow may fall to 25% of the resting value when strenuous work is performed. The combination of sympathetic nervous activity and the release of catecholamine substances is involved in this process. The reduction of renal blood flow during exercise produces a concomitant effect on the glomerular filtration rate, though the latter decreases relatively less than the former during exertion. However, the degree of hydration has an important influence on the glomerular filtration rate. An antidiuretic effect is observed during intense exercise. Changes in urine flow are dependent on the plasma antidiuretic hormone levels which are increased by intense exercise. Heavy exercise has an inhibitory effect on most electrolytes (Na, Cl, Ca, P). With potassium, however, most studies report that potassium excretion is not consistently affected by moderate to heavy exercise. Increased aldosterone production helps the body to maintain sodium by increasing its reabsorption from the filtered tubular fluid. Recent studies suggest that sympathetic stimulation may be involved during exercise. Strenuous work leads to an increased excretion of erythrocytes and leucocytes in urine. Cylindruria has been regularly found in postexercise urine in different sports. Postexercise proteinuria is a common phenomenon in humans. It seems to be directly related to the intensity of exercise, rather than to its duration. This excretion of proteins in urine is a transient state with a half-time of approximately 1 hour. Postexercise proteinuria has a pattern different from normal physiological proteinuria. Immunochemical techniques demonstrate that postexercise proteinuria is of the mixed glomerular-tubular type, the former being predominant. The increased clearance of plasma proteins suggests an increased glomerular permeability and a partial inhibition of tubular reabsorption of macromolecules. Haemoglobinuria and myoglobinuria may be observed under special exercise conditions. The degree of hydration appears to be important to reduce these abnormalities.

Biochemical changes in a 100 km run: free amino acids, urea, and creatinine

Free amino acids, urea, and creatinine were analyzed in venous blood and urine of 11 trained (28--81 years old) male subjects before, immediately after, and 1 day after a 100 km running competition. The urinary excretion per minute of all amino acids was lowered after the contest. The renal clearance of creatinine was reduced from 116 to 60 ml/min and the clearance of most amino acids was reduced to a similar extent. However, for the amino acids with a resting clearance under 1 ml/min (x), a high relative clearance ratio (y in % of x) was seen post-exercise: y = -92.3 (log10 x) +23.1, r = -0.83, showing that their high reabsorption capacity had been impaired. Serum concentrations of most free amino acids, including the branched-chain amino acids and alanine, were reduced to 35--85% of the pre-race values. The sulfur amino acids were elevated either at the end of (cystine, to 180%) or 24 h after (methionine, to 155%) the race. Urea production increased by 44% while creatinine production tended to decrease. The production of 3-methylhistidine remained unchanged. These findings are compatible with a stimulation of gluconegenesis at the expense of the amino acid pool without induction of muscle protein catabolism.

Biochemical changes in a 100 km run: proteins in serum and urine

Eleven male subjects took part in a 100 km running competition. Alterations in the total plasma protein and in ten individual plasma protein concentrations in blood and urine were measured prior to the run, immediately after and after 1 day of recovery. Five individual proteins showed a 7-10%, and lysozyme a 40%, increase in the plasma after the run. On the contrary, the haptoglobin concentration fell to 40% of its pre-race level. None of these variations were correlated with the plasma volume change. The present data showed a moderate hemolysis, as evidenced by plasma lysozyme and hemoglobin-haptoglobin binding. The urinary excretion of plasma proteins was slightly increased, especially albumin and alpha1-acid-glycoprotein. The renal clearance of plasma proteins revealed that the 100 km run induced a moderate increase of glomerular permeability without any signficant change in the tubular reabsorption process.

Lactate uptake by inactive forearm during progressive leg exercise

Eleven male subjects were studied during graded leg exercise from 60 to 270 W. Arterial and venous lactate concentrations were measured from the resting forearm during the exercise and recovery periods. Lactate concentration rose regularly during the work and declined slowly to basal levels after the exercise. The arteriovenous difference rapidly became positive during the exercise, indicating a net uptake of lactate by the nonexercising muscles. The uptake of lactate by the muscle correlated directly with the arterial concentration. After the 5th min of recovery, there was no longer any significant difference between arterial and venous lactate concentrations. It is concluded that 1) nonexercising muscles play a small role in the removal of lactate during exercise and 2) significant removal of lactate from the blood by nonexercising muscles stops soon after the cessation of exercise.

Renal glomerular and tubular impairment during strenuous exercise in young women

Creatinine, total protein, albumin and beta2-microglobulin were measured in the urine of fifteen healthy women before and after strenuous short-term exercise. The heavy intermittent load produced an increased urinary excretion of total protein, albumin and beta2-microglobulin, while creatinine was unaffected. The renal clearance of albumin and beta2-microglobulin showed very high values after stopping the exercise. However, 45 min after the end of exercise, total protein returned to initial values while albumin and beta2-microglobulin remained high. The urinary ratio between beta2-microglobulin and albumin is higher in urine collected after exercise than in normal proteinuria. This implies that post-exercise proteinuria is of glomerular and tubular origin.