| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Yoji Ehime University, Faculty of Medicine, Instructor, 医学部, 助手 (20226567)
TATEISHI Norihiko Ehime University Hospital, Associate Professor, 医学部附属病院, 助教授 (90236555)
TANAKA Junya Ehime University, Faculty of Medicine, Professor, 医学部, 教授 (70217040)
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| Research Abstract |
Effects of blood flow and hemorheological factors on oxygen (O_2) transport to brain and cerebral activity were comprehensively studied in microcirculatory level, in addition to the fundamental studies.
(1) Red blood cell (RBC) flow in microvessels varied in proportion to blood flow in main arteries. Close relationship between oxygenation state of blood and blood flow condition was observed.
(2) Effects of theological properties of RBCs on O_2 release were demonstrated using an O_2-permeable narrow tube, in relating to O_2 diffusion distance in RBCs and the surroundings.
(3) Oxygenation-deoxygenation process of blood affected RBC aggregation by pH-/CO_2-dependent shape changes of RBCs, and the enhancement of O_2 release was suggested at low pH and high CO_2 conditions.
(4) High-fat meal, even temporarily, enhanced RBC aggregation by increased triglycerides concentration in blood plasma. The phenomenon suggested microcirculatory disturbances and a risk for arteriosclerosis.
(5) Two-dimensional images of RBC flow and the oxygenation state in microvascular network, in addition to their cross-sectional images in single microvessels, were successfully constructed for brain cortex and mesentery.
(6) Flow behavior of RBCs in microvessels was changed more strikingly by vascular and hemorheological factors, as compared to their behavior in artificial narrow tubes. The phenomena were mainly due to the elasticity of the flow channels, such as in atherosclerotic change of blood vessels.
(7) Neural activity in brain was markedly influenced by O_2 transfer to the tissues through blood flow, as evaluated by evoked potential in sensory area.
(8) Mutual control mechanisms by humoral factors were found between functions of neurons and microglia.
In conclusion, this study strongly suggested that cerebral functions were influenced by O_2 transfer, which was modified not only by blood vessel factors, but also by hemorheological factors.
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