Erythropoietin and its receptor in human skeletal muscle

Abstract

Erythropoietin receptor (EPOR) expression in adult skeletal muscle has not been reported to date. Our aims were to investigate if human skeletal muscle expresses EPOR and whether there is an exercise-induced uptake of erythropoietin (EPO) over the exercising leg. Ten healthy male subjects performed 65 min of cycle exercise. Vastus lateralis muscle biopsies were obtained and arterio-venous concentration differences were measured over the exercising leg. EPOR protein was expressed in the skeletal muscle in areas corresponding to the sarcolemmal region and EPOR mRNA expression was increased by exercise. There was a small uptake of EPO at rest. In contrast, during exercise there was a small release of EPO from the exercising leg. In conclusion, these findings indicate that skeletal muscle should be integrated into the wider context of the biological role of EPO. In a clinical context, activation of EPOR in skeletal muscle could be an additive mechanism, complementary to increased amount of erythrocytes, behind the enhanced exercise capacity seen in patients treated with recombinant EPO.