[Rearrangement of the hemodynamic mechanisms of orthostatic tolerance of humans on long-term space missions].
Orthostatic tolerance (OT) was evaluated in 25 cosmonauts using the traditional standing test before and after space fights of about six months in length; 15 cosmonauts of this group were also subjected to ultrasonic investigation during the lower body negative pressure test before, during and after long-term SF. Efficiency of the OT vascular mechanisms was gradually falling and stabilized at the end of six-month SF at a level significantly below pre-flight level. Post-flight OT recovery took longer time as compared with short-term SF suggesting more profound shifts in the vascular control system. Ultrasonic monitoring of blood flow along the aorta, medial cerebral artery and femoral artery enabled more comprehensive and reliable evaluation of the vascular tone and circulation control and appeared more informative than the traditional recording of integral indices, i.e. HR and BP.
Fomina
G A
GA
Kotovskaia
A R
AR
Pochuev
V I
VI
Zhernakov
A F
AF
D000328:Adult; D001011:Aorta / Q000000981:diagnostic imaging / Q000502:physiology; D018493:Cardiovascular Deconditioning / Q000502:physiology*; D015444:Exercise / Q000502:physiology; D005260:Female; D005263:Femoral Artery / Q000000981:diagnostic imaging / Q000502:physiology; D005500:Follow-Up Studies; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008150:Lower Body Negative Pressure; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000502:physiology; D013026:Space Flight; D014463:Ultrasonography