PRINCIPAL INVESTIGATOR(S ): John P. Meehan, and Roland D. Rader 



EXPERIMENT TITLE/NUMBER : Cardiovascular Observations of the Macaca nemestrina 



Monkey in Biosatellite III 



PROGRAM/MISSION : Biosatellite III 



CLASSIFICATION : Animal - Pig-tailed monkey ( Macaca nemestrina ) 



DISCIPLINE(S) : Cardiovascular 



OBJECTIVES : To determine the physiological effects of Earth orbit on nonhuman 

 primates, to provide insights into possible hazards associated with long-term 

 space flights, and to acquire information on basic physiological adjustments 

 to extended weightlessness, particularaly concerning the cardiovascular 

 system. 



PROTOCOL : Inflight vascular pressures were obtained by catheterization 

 techniques and recorded without amplification on an orbital galvanometric 

 oscillograph. One pair of electrodes provided electrocardiographic and 

 respiratory information. Four indwelling catheters, two venous and two 

 arterial, yielded redundant pressure measurements. Heparin pumps were used to 

 keep the catheters clear. There were four ground control monkeys, plus 

 baseline data from the flight monkey for comparative analysis. 



EQUIPMENT : Catheters, orbital galvanometric oscillograph, ECG electrodes. 



RESULTS : The flight subject experienced an immediate sustained increase in 

 central venous pressure resulting from a central pooling of blood volume. 

 This shift in blood volume is thought to have initiated the Gauer-Henry 

 mechanism whereby urine volume was initially maintained at a high level. This 

 coupled with a high evaporative fluid loss, produced an early dehydration 

 probably associated with electrolyte imbalance. Venous pressure started to 

 fall on Day 5, while arterial pressure and heart rate were within 

 physiological limits until Day 8, i.e., near the termination of the flight. 



CONCLUSIONS : There was a shift of blood volume toward the heart. The 

 observed increase in atrial pressure of 2-3 cm Ho was large enough to provide 

 a stimulus for the loss of body fluid described by Gauer and Henry. 

 Weightlessness and hypothermia acted to shift blood volume centrally. This 

 provided a strong drive for the reduction of blood volume. Restraint, unusual 

 vestibular sensations, and the continuing polydipsia all acted to disturb the 

 central mechanisms which might have acted to restore normal control and 

 regulation of salt and water metabolism. There were a number of factors all 

 acting in concert which may have prevented the effective adaptation of the 

 monkey to the environment. 



PUBLICATIONS : 2, 3, 4, 7, 387, 389, 390, 391, 392, 556 



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