Screening for recombinant human erythropoietin using [Hb], reticulocytes, the OFF(hr score), OFF(z score) and Hb(z score): status of the Blood Passport

Haemoglobin concentration ([Hb]), reticulocyte percentage (retic%) and OFF(hr score) are well-implemented screening tools to determine potential recombinant human erythropoietin (rHuEpo) abuse in athletes. Recently, the International Cycling Union implemented the OFF( z score) and the Hb( z score) in their anti-doping testing programme. The aim of this study is to evaluate the sensitivity of these indirect screening methods. Twenty-four human subjects divided into three groups with eight subjects each (G1; G2 and G3) were injected with rHuEpo. G1 and G2 received rHuEpo for a 4-week period with 2 weeks of "boosting" followed by 2 weeks of "maintenance" and a wash-out period of 3 weeks. G3 received rHuEpo for a 10-week period (boost = 3 weeks; maintenance = 7 weeks; wash out = 1 week). Three, seven and eight of the 24 volunteers exceeded the cut-off limits for OFF(hr score), [Hb] and retic%, respectively. One subject from G1, nobody from G2, and seven subjects from G3 exceeded the cut-off limit for Hb( z score.) In total, ten subjects exceeded the cut-off limit for the OFF( z score); two subjects from G1, two subjects from G2 and six subjects from G3. In total, indirect screening methods were able to indicate rHuEpo injections in 58% of subjects. However, 42% of our rHuEpo-injected subjects were not detected. It should be emphasised that the test frequency in real world anti-doping is far less than the present study, and hence the detection rate will be lower

Hypoxia increases exercise heart rate despite combined inhibition of β-adrenergic and muscarinic receptors

Hypoxia increases the heart rate response to exercise, but the mechanism(s) remains unclear. We tested the hypothesis that the tachycardic effect of hypoxia persists during separate, but not combined, inhibition of β-adrenergic and muscarinic receptors. Nine subjects performed incremental exercise to exhaustion in normoxia and hypoxia (fraction of inspired O2 = 12%) after intravenous administration of 1) no drugs (Cont), 2) propranolol (Prop), 3) glycopyrrolate (Glyc), or 4) Prop + Glyc. HR increased with exercise in all drug conditions (P 0.4) but larger during Prop (3.4 ± 1.6 l/min, P = 0.004). Our results demonstrate that the tachycardic effect of hypoxia during exercise partially relies on vagal withdrawal. Conversely, sympathoexcitation either does not contribute or increases heart rate through mechanisms other than β-adrenergic transmission. A potential candidate is α-adrenergic transmission, which could also explain why a tachycardic effect of hypoxia persists during combined β-adrenergic and muscarinic receptor inhibition

Alterations of systemic and muscle iron metabolism in human subjects treated with low-dose recombinant erythropoietin

The high iron demand associated with enhanced erythropoiesis during high-altitude hypoxia leads to skeletal muscle iron mobilization and decrease in myoglobin protein levels. To investigate the effect of enhanced erythropoiesis on systemic and muscle iron metabolism under nonhypoxic conditions, 8 healthy volunteers were treated with recombinant erythropoietin (rhEpo) for 1 month. As expected, the treatment efficiently increased erythropoiesis and stimulated bone marrow iron use. It was also associated with a prompt and considerable decrease in urinary hepcidin and a slight transient increase in GDF-15. The increased iron use and reduced hepcidin levels suggested increased iron mobilization, but the treatment was associated with increased muscle iron and L ferritin levels. The muscle expression of transferrin receptor and ferroportin was up-regulated by rhEpo administration, whereas no appreciable change in myoglobin levels was observed, which suggests unaltered muscle oxygen homeostasis. In conclusion, under rhEpo stimulation, the changes in the expression of muscle iron proteins indicate the occurrence of skeletal muscle iron accumulation despite the remarkable hepcidin suppression that may be mediated by several factors, such as rhEpo or decreased transferrin saturation or both