Activation of respiratory sinus arrhythmia in monkeys during space flight
Mel'nichenko V.P.; Badakva, A.M.; Evstratov, Y.A.; Drozdov, I.N.; Magedov, V.S.
Kosmicheskaia Biologiia i Aviakosmicheskaia Meditsina 25(3): 25-28
1991
ISSN/ISBN: 0321-5040 PMID: 1770761 Document Number: 374318
During the first day in space the rhesus monkey, called Vernyi, flown on Cosmos-1667 showed higher values of the daytime, night, and daily respiratory sinus arrhythmia (RSA) when compared to those observed before launch and before or the first day of the simulation study. During orbital flight, the mean daily value of RSA was in the range 13.08-16.00 beats/min. In the simulation study, this parameter increased from 4.68 beats/min during the first day to 15.16 beats/min on the 6th day. The mean RSA values during days 1 through 3 were significantly higher in real than in simulation flight. Analysis of rheopneumograms revealed a correlation between respiration parameters and RSA variations. In space, there was no correlation between RSA and HR, which was reported in the simulation study (r = -0.625). Assuming that RSA is a noninvasive indicator of parasympathetic control over cardiac rhythm, it can be postulated that the primate body adpated to microgravity via activation of parasympathetic mechanisms controlling the heart function.