es in human muscle proteome following prolonged Epo administration. In the current study two different doses of rHuEpo was investigated. In study A, a dose of 15,000 IU was administrated, which is comparable to the doses used to treat patients with end-stage renal disease. In study B, an even higher dose, comparable to the dose employed to treat patients with stroke, was used. Based on the presence of the Epo-R in skeletal muscle tissue, we hypothesized that rHuEpo treatment would lead to activation of STAT5, p38-MAPK, Akt, Lyn, IKK, and p70S6K downstream of the Epo-R, which would lead to changes in the skeletal muscle protein content. Methods Subjects and ethical approval Acute studies. In study A, eight healthy male subjects were included, all of whom provided a written informed consent to participate in the study, which was approved by the local human ethical committee of Copenhagen and Frederiksberg, in adherence to the declaration of Helsinki. Data related to changes in mRNA content among these subjects have previously been published. In study B, ten healthy young men were enrolled. All subjects provided a written informed consent to participate in the study, which was approved by the local human ethical committee of Central Denmark Region, in adherence to the declaration of Helsinki. Prolonged study. Eight healthy male volunteers were included. All subjects provided a written informed consent to participate in the study, which was approved by the local human ethical committee of Copenhagen and Frederiksberg, Denmark, in adherence to the declaration of Helsinki. Results describing basic serum hematological changes after Epo administration to these subjects have already been published. The subjects 
arrived fasting at the lab and were served a light standardized breakfast Chlorphenoxamine biological activity adjusted for body weight and activity level; a blood sample and the first biopsy were collected 2 hours later after resting in the supine position. The biopsies were collected from m. vastus lateralis and taken before and 2 h, 4 h, 6 h, and 10 h post I.V. administration of either rHuEpo or placebo. Biopsies were immediately frozen in liquid nitrogen, and stored at 280uC until further analysis. After the 6 h biopsy, the subjects were served a standardized meal. Blood samples were taken at the same timepoints as the biopsies, centrifuged at 25006 PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/22189475 g for 15 minutes, and stored at 220uC until analysed. Biopsies from before injection of rHuEpo/placebo and 2 h, 4 h, and 6 h post, were used for protein extraction and western blotting. The 10 h post biopsy was used for mRNA quantification. Study B had a single-blind, randomised, placebo-controlled, cross-over design with a 14-day wash-out period in-between. Before enrolment, the subjects were examined by a medical doctor to ensure general health and standard blood analysis, and electrolyte balance) was performed. The subjects were examined on two occasions: 1) i.v. treatment with 400 IU/kg Eprex or 2) placebo, both administered at t = 0 min. The subjects arrived fasting at the lab in the morning. Muscle biopsies were collected from m. vastus lateralis and taken one hour after Epo/saline administration. The biopsies were immediately frozen in liquid nitrogen and stored at 280uC until further analysis. Serum and plasma were collected 4 h post treatment, centrifuged and stored at 220uC. Prolonged study. Muscle biopsies from m. vastus lateralis were collected approximately 1 week before the first Epo injection. Epo was injected
