Bone Abstracts

Microgravity causes adverse health problems to astronauts during space flight, especially to bone, heart, and muscles. The vascular system plays a central role in various organs and the skeletal tissues. This new environment makes vascular adaptation difficult. Nitric oxide plays an essential role in the vascular system by modulating basal vascular tone. An alteration of NO metabolism or bioavailability has been thought to be one of the main factors for vascular disorders. Restoring NO equilibrium in the system has been proposed as a promising therapeutic tool in alleviating vascular problems in space or post space travel. Blood vessels are lined with endothelium, an expansive cell layer with total surface area of 4000–7000 m² in an average-sized human. Therefore, alteration in endothelial NO is anticipated to perturb vessel health. Results of this study demonstrated that exposure of the endothelium to limited periods (2–24 h) of microgravity resulted in elevated NO production and faster growth and development of vascular tubes in both in vitro and in ovo models. To understand the elevated NO perturbations in heart under microgravity we investigated the cardiac functions using Chick embryo and zebra fish as models to determine heart rate under microgravity. Results showed that in the presence of NO, the rate of heart beat increased significantly under microgravity. Removal of NO resulted in heart beat returning to normal. Results suggest that administration of NO based therapy to astronauts during space flight could potentially overcome microgravity mediated vascular problems and improve the performance of heart, through which other organs, including bone, could be rescued to a nearly normal condition.