[Ground-based studies on thermoregulation at simulated microgravity by head-down tilt bed rest]

Comparisons of headward fluid shifts, plasma volume losses, altered vasodilator and vasoconstrictor responses, reduced exercise capacities, etc. between microgravity and head-down tilt (HDT) bedrest suggested that HDT model was suitable for simulating thermoregulation under microgravity. Both microgravity and simulated microgravity by HDT exposures degraded human thermoregulation ability in some aspects. The features of the responses to heat stress on men after HDT exposures were higher increase rate in rectal temperature, attenuated increase rates of skin temperature and body heat conductance, less heat dissipation from core to skin and higher sensitivity of sweating etc.