Antiorthostatic suspension for 14 days does not diminish the oxidative response of neutrophils in mice

The effects of long-term spaceflight on inflammatory responses have not bee n well-studied in either humans or animals. It is thus important to determi ne if the functions of immune and inflammatory cells are altered in models of spaceflight. One such animal model is antiorthostatic suspension (AOS), in which the experimental animal is subjected to a head-down tilt that mimi cs both the stress and the cephalad fluid shift experienced in spaceflight. A previous study reported that the peritoneal neutrophils from mice experi encing AOS generated less superoxide than unsuspended controls. We expanded on this study using several different stimuli and measuring the oxidative response of murine neutrophils in a variety of ways. These responses includ ed the rate, lag period, and dose/response characteristics for superoxide g eneration, FAGS analysis with dihydrodichlorofluorescein as a substrate, an d a chemiluminescence response with luminol as a substrate. We also examine d phagocytosis of three different microorganisms. While some effects of ort hostatic suspension (attributable to the stress of the apparatus) were obse rved, no clear effects of AOS on oxidative function of the peritoneal neutr ophils were seen.