Abstract des Autors

In the present experiment we have studied the effect of exercise performed before and 24 h after withdrawal of 450 ml of blood on the serum erythropoietin and growth hormone (GH) levels, in humans. Twelve male subjects (x ± SD) aged 23.2 ± 2.6 y, with a body mass of 74.8 ± 7.2 kg, height 178.0 ± 7.6 cm, BMI 23.6 ± 2.1 kg × m-2, VO2max 2937 ± 324 ml/min, participated in this study. The subjects performed twice an incremental exercise test until exhaustion, separated by a period of about 7 - 10 days. The second test was performed 24 h after withdrawal of 450 ml of blood (honorary blood donation). In the control study we found no effect of the incremental exercise on the serum erythropoietin concentration, which amounted to 14.24 ± 7.66 mU/ml at rest and 14.97 ± 6.07 mU/ml at the end of the incremental test. Serum GH level in the control study rose considerably from 0.158 ± 0.024 nmol/l at rest to 1.523 ± 0.336 nmol/l at the end of exercise and returned to initial value 2 h after the exercise. During the experiment performed 24 h after withdrawal of 450 ml of blood the serum erythropoietin concentration at rest was significantly elevated (p<0.01) in relation to the control measurement (amounting to 24.85 ± 13.60 mU/ml) and at the end of the incremental exercise a ten-dency towards further elevation (p=0.09) in erythropoietin concentration up to 28.32 ± 14.51 mU/m was observed. Serum GH level during the experiment after blood withdrawal was similar to that in control test and exercise caused a rise in the GH level to 1.056 ± 0.52 nmol/l, significantly less than in control test, but this increment fell to control value 2 h after exercise. The elevated level of erythropoietin 24 h after blood withdrawal was accompanied by a signifi-cant increase (p<0.015) in blood hydrogen ion concentration [H+]b at rest from 48.2 ± 2.8 nmol/l in the control study to 52.9 ± 4.5 nmol/l after blood donation. No effect of blood withdrawal on pre-exercise level of plasma lactate concentration, end-tidal O2 and end-tidal CO2 was found. We concluded that withdrawal of 450 ml of blood, within 24 hours significantly increased serum erytropoietin concentration and caused non-lactic acidosis. A single bout of maximal incremental exercise, performed before and 24 hours after blood withdrawal, had no effect on serum erythropoietin concentration in humans but the exercise-induced increase in serum GH concentration performed after blood withdrawal tended to be lower than in the control study. Verf.-Referat