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Time-Dependent Changes in Cerebral Blood Flow and Arterial Pressure During Mild +Gz Hypergravity.

BACKGROUND
Artificial hypergravity has been proposed to prevent or treat various forms of physiological deconditioning experienced during spaceflight. We have previously reported that cerebral blood flow decreased at 15-21 min of +1.5-Gz centrifugation without decreases in arterial pressure at heart level. We reanalyzed our previous data to clarify time-dependent changes in cerebral blood flow and arterial pressure during mild +Gz hypergravity.


METHOD
We reanalyzed data for 0-20 min during +1.5-Gz centrifugation on 13 male subjects for whom physiological data were steadily recorded. Mean cerebral blood flow velocity in the middle cerebral artery (MCBFVMCA), mean arterial pressure at heart level (MAPheart), and middle cerebral artery level (MAPMCA) during centrifugation were averaged every 5 min and compared with prehypergravity data (+1.0 Gz, 5 min).


RESULTS
MAPheart did not change significantly, but MAPMCA decreased significantly throughout centrifugation compared to prehypergravity data (-16.7% to -24.7%). MCBFVMCA tended to be decreased at 0-5 min of +1.5-Gz centrifugation (-3.3%), but this was not statistically significant. MCBFVMCA was significantly decreased at 5-10 min (-5.5%). MCBFVMCA at 10-15 min and 15-20 min were also significantly decreased to almost the same level (-6.9% and -6.8%, respectively).


DISCUSSION
No significant change in MAPheart was detected, whereas MAPMCA decreased significantly from the beginning of +1.5-Gz centrifugation. On the other hand, MCBFVMCA gradually decreased and became roughly flat in the latter half of 20-min centrifugation. Understanding the different time-dependent changes in cerebral blood flow and arterial pressure under mild +Gz hypergravity might be important for implementation of centrifuging as a countermeasure for spaceflight-induced deconditioning.Konishi T, Kurazumi T, Kato T, Takko C, Ogawa Y, Iwasaki K. Time-dependent changes in cerebral blood flow and arterial pressure during mild +Gz hypergravity. Aerosp Med Hum Perform. 2018; 89(9):787-791.