[Vascular mechanisms of adaptation to head-down tilt body posture].
Using occlusion plethysmography and rheography, the state of peripheral circulation of 18 test subjects during 25 exposures to head-down tilt was investigated. The test subjects were subdivided into two groups: nine subjects actively changed their body position by 90 degrees and nine others were passively transferred to the head-down position at an angle of -12 degrees. It was found that regular training facilitated the development of vascular mechanisms which assisted adaptation to the head-down tilt: it decreased the tone of resistance vessels of the arms and legs and that of capacitance vessels of the legs; it increased the tone of cerebral resistance and capacitance vessels. The tone of leg capacitance vessels varied, depending on the type of training: passive tilting increased their compliance and active tilting decreased it. The final result of the tone redistribution in the peripheral vascular bed during training was a smaller increase of head blood content and a smaller fluid outflow from the legs.
D000222:Adaptation, Physiological; D001132:Arm / Q000098:blood supply*; D001808:Blood Vessels / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D010991:Plethysmography / Q000379:methods; D011187:Posture; D012039:Regional Blood Flow; D013997:Time Factors; D014655:Vascular Resistance
Sosudistye mekhanizmy adaptatsii k antiortostaticheskogo polozheniiu tela.