Abstract

Physical activity as well as sojourn at altitude causes decreasing oxygen tension in the tissues. To maintain a sufficient oxygen delivery, adaptive proc-esses are induced. Under the reduction of oxygen the transcription factor HIF–α1 stabilizes and induces the release of regulating proteins like vascular endothelial growth factor (VEGF) and Erythropoietin (EPO). These factors are well known as key players in proangiogenetic processes. On the cellular level an increasing number of stem cells can be detected in the circulation as a response to the low oxygen tension. The stem cells - like mesenchymal stem cells (MSC) - play a major role in regeneration and remodeling processes which leads to the formation of new vessels or tissue repair. To study the influence of hypoxia on the cellular and cytokine level two studies have been carried out. Study I focuses on the MSC and study II investigates changes at the cytokine level. Einleitung