The effect of microgravity on the autonomic nervous system of rhesus monkeys.

Gastric myoelectric activity and respiratory sinus arrhythmia of two monkeys flown on Bion 11 were investigated. During flight, vagal effects on cardiac and gastric function of the two animals varied differently: in one animal they decreased at an early flight stage and returned to the control level by the end of flight, whereas in the second monkey the trend was the opposite. The decrease was accompanied by space motion sickness symptoms.