Medicine & Science in Sports & Exercise:
F-36 Free Communication/Poster - Supplements III (Creatine, Sodium Bicarbonate, Others): JUNE 3, 2011 1:00 PM - 6:00 PM: ROOM: Hall B
Christensen, Britt; Sackmann-Sala, Lucila; Cruz-Topete, Diana; Jørgensen, Jens Otto L.; Jessen, Niels; Lyndby, Carsten; Kopchick, John J.
1Aarhus University Hospital, Aarhus C, Denmark. 2Ohio University, Athens, OH. 3University of Zürich, Zürich, Switzerland.
(No relationships reported)
INTRODUCTION: Erythropoietin (Epo) is mainly produced in the kidney upon low blood oxygen tension to stimulate erythropoiesis in the bone marrow. Recombinant human Epo (rHuEpo), a drug developed to increase arterial oxygen content in patients, is also illicitly used by athletes to improve endurance performance. Therefore, a robust and sensitive test to detect its abuse is needed.
PURPOSE: The aim of the present study was to investigate potential human serum biomarkers of Epo abuse using a proteomic approach.
METHODS: Eight healthy male subjects (25 ± 4 yr, 183 ± 6 cm, 79 ± 7 kg) were injected s.c. with rHuEpo (5000 IU) every second day for a 16-day period. Serum was collected before, 8 and 16 days after treatment. For proteomic analysis, the samples were homogenized and proteins separated by two dimensional (2D)-gel electrophoresis. Protein spots that changed significantly (p<0.05) in response to rHuEpo treatment were identified by mass spectrometric (MS) analysis.
RESULTS: At baseline, all measured hematological parameters of the individuals were within normal ranges. Both the number of reticulocytes and erythrocytes increased throughout the study, leading to a significant increase in hematocrit (0.44 vs 0.46, p=0.01) and hemoglobin (9.24 vs. 9.68 mmol/l, p=0.008) content at day 16. In addition, transferrin levels increased (32.8 vs. 37.4 μmol/l, p<0.01) but the percentage of iron bound to transferrin (0.30 vs 0.13, p<0.001) and ferritin levels (115 vs. 24 μg/l, p<0.001) decreased. The proteomic analysis showed 97 serum protein spots, out of these was seven found to decrease at day 16 compared to pre-Epo administration. The spots were identified as four isoforms of haptoglobin (p=0.014, p=0.006, p=0.013, p=0.047), two isoforms of serotransferrin (p=0.018, p=0.047) and a mixture of hemopexin and albumin (p=0.050). No protein spots were significantly altered eight days after the start of Epo injections.
Conclucion: The decrease in isoforms of three different proteins was consistent in all subjects, indicating that these proteins could be future markers of Epo abuse. Thus, a 2D-gel electrophoresis proteomic approach appears feasible for generating novel markers of Epo abuse. Effects of exercise and hypoxia on these biomarkers have to be evaluated before implementing them in a future anti-doping test.