The effect of chamber restraint (with or without lower body positive pressure) on hematopoiesis (particularly erythropoiesis) in squirrel monkeys (Saimiri sciureus).

Squirrel monkeys, restrained in lower body positive pressure (LBPP) chambers in attempts to model the space flight-induced hematological consequences of a cephalad fluid shift, showed a decrease in red blood cell mass which was largely independent of actual LBPP. The only LBPP-specific hematological effect was an alteration in red blood cell (RBC) survival. This monkey model represents the second, ground-based animal system in which this phenomenon has been recorded and shown to be unique to a cephalad fluid shift. These data suggest a re-evaluation is necessary of the role of altered RBC clearance as a contributing factor to the anemia of space flight in humans.