In order to examine structural and mechanical influences of resistance vessel wall on the metabolic and myogenic mechanisms of peripheral flow control, a dynamic ( five-element analogue ) model for resistance vessel wall is introduced. The dynamic model here used is complex and is represented by a Maxwell model connected in series with the three-component Hill model. The metabolic effects on myogenic mechanism are inserted in Hill's contractile elements. The mechanical behavior of resistance vessel wall during autoregulatory flow control is calculated in comparison with experimental data to be explained well by the dynamic model. The elastic modulus (K₁) of parallel elastic element and the reactivity of vascular smooth muscle are suggested to play an important role in blood flow autoregulation. In particular, the upper and lower limits of pressure in blood flow autoregulation shift to higher region of arterial pressure with the increases of the elastic modulus K₁ and myogenic contractile force so that the effectiveness of the myogenic mechanism is reduced. The wall tension is resettled at lower levels by myogenic contractile responses. (J. Jpn. Soc. Biorheol., 1 (4), 212~219, 1987).

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The characteristics of pressure-wave propagation through a brachial artery simulated by a thin walled silicone rubber-tube, a part of which was compressed externaly by pneumatic cuff, was studied experimentally when the pressure at the proximal end of the tube was given as a boundary condition. The amplitude and the shape of the pressure-waves traveling downstream through the arteries proximal and distal to the cuff strongly depend on the artery length between the aorta and the cuff. Only when the length is short enough, the magnitude of the cuff pressure when the first and the last Korotkoff sound are monitored can be closely related to the systolic and the diastolic pressure at the artery proximal end (the aorta pressure). ( J. Jpn. Soc. Biorheol., 1 (4), 220~229, 1987.)

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The role of erythrocyte deformability and vasculature in a blood flow was investigated from pressure-flow rate relation of erythrocyte suspension in the perfusion of bullfrog's hind limbs. The pressure-flow rate relation was constructed by a vertical-tube method ( Nichol, J. et al., Am. J. Physiol. 1951 ) with a slight modification. For the evaluation of red cell deformability, hind limbs were fixed by perfusing glutaraldehyde solution. The perfusion of several stages of echinocytes or stomatocytes in fixed hind limbs showed the decrease in the rate of flow or the increase in the resistance to flow. Thus the hind limb perfusion method ( whether intact or fixed ) provides an unique aspect in the study of red cell deformability and the hemodynamic action of vasculature. The uninjured intact vascular vessels were able to compensate lowered erythrocyte deformability in a flow to a considerable extent. On the other hand, chlorpromazine-treated vascular bed enhanced synergetically the disturbance of blood flow caused by undeformable erythrocytes. These results reveal clearly an important role of vasculature as well as red cell deformation in a maintenance of blood flow. It can be concluded that the present study provides significant implications in understanding the link between in vitro experiment and in vivo situation. (J. Jpn. Soc. Biorheol., 1 (4), 230~,240, 1987)

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