Reactive hyperemia of Upper limb in man

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  • ヒト上肢における反応性充血について
  • ヒト ジョウシ ニ オケル ハンノウセイ ジュウケツ ニ ツイテ

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The reactive hyperemia of finger and forearm was studied in man by using a high sensitive plethysmograph and the results were analyzed and discussed from the view point of rheological fluid dynamic theories. 1) The reactive hyperemia increased in relation to the occlusion time of 3, 6, and 12 minutes, and also to the increment of temperature ranging from 21℃ to 42℃. 2) The equation below was mainly used in the present study : Q=πR^4/8ηL・&lrtri;P・F(ξ), with ξ=2Lf/PR, where R, radius of capillary ; &lrtri;P, pressure difference between arteriolar and venular ends of capillaries, when ξ determined blood flow in a capillary with non-permeable wall and is regarded as stable in microcirculation, where pressure gradient is constant, and equation : f=K・Hct^3, T=P・R (Hct : hematocrit, T : tension) is satisfied. Volume pulse increased when the occlusion is released. Accordingly, it is concluded that arteriolar tension of muscular vessel in the forearm is relaxed during occlusion. From the view point of fluid exchange between tissue and capillary with permeable wall, the significance of reactive hyperemia is stated as follows. During occlusion of about 10 minutes, &lrtri;α/&lrtri;P is smaller than 1/2 (tissue fluid loss) in the equation of Q=πR^4/8ηL・&lrtri;P・{1+εf(√<1/3>, &lrtri;α/&lrtri;P)}. At release, &lrtri;α/&lrtri;P becomes larger than 1/2 (tissue fluid gain) and loss of tissue fluid is recovered between the initial phase and peak of reactive hyperemia. Next balanced state where &lrtri;α/&lrtri;P equals 1/2 is attained by the shift of excess fluid from tissue to capillary. The peak increment of reactive hyperemia was relatively small even after occlusion of more than 10 minutes. This implies that there is limits in the loss of tissue fluid and that the extra fluid, which might be required for longer anaerobic activity of skeletal muscle, has moved into tissue during occlusion and the same amount of fluid may flow out of tissue into capillary at release, for maintaining tissue homeostasis. As the results of situation explained above, hemodilution occurs, which is exactly seen as a decrease in colloid osmotic pressure. It is concluded that the microcirculatory significance of reactive hyperemia in man is essential for the maintenance of tissue fluid homeostasis.

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