Acute physiological responses of squirrel monkeys exposed to hyperdynamic environments

Area of Science:

• Aerospace Medicine
• Primate Physiology
• Gravitational Biology

Background:

• Understanding primate physiological and behavioral responses to hyperdynamic environments is crucial for spaceflight safety.
• Squirrel monkeys serve as a relevant model for studying human responses to extreme gravitational forces.

Purpose of the Study:

• To investigate the physiological and behavioral effects of acute hyperdynamic exposures on squirrel monkeys.
• To assess the susceptibility of primates to simulated launch and re-entry G-force profiles.

Main Methods:

• Four restrained squirrel monkeys underwent baseline monitoring at 1 G.
• Monkeys were exposed to sustained +2 Gz, simulated space shuttle launch (+2.9 Gz max), and re-entry (+1.7 Gz max) profiles.
• Colonic temperature, heart rate, and behavior were continuously recorded during and after exposures.

Main Results:

• Colonic temperature decreased by up to 2°C during hyperdynamic exposures, contrasting with stable baseline temperatures.
• Heart rate showed significant elevations during centrifugation, returning to baseline levels post-exposure.
• Behavioral changes included drowsiness and sleep onset during centrifugation, with alertness observed during baseline periods.

Conclusions:

• Primates, specifically squirrel monkeys, exhibit significant physiological and behavioral changes when subjected to acute hyperdynamic environments.
• These findings highlight the susceptibility of primates to extreme G-forces, with implications for human spaceflight.
• Further research is warranted to understand the full impact of hyperdynamic stress on primate physiology.