Coronary blood velocity waveforms and velocity spectra were evaluated in 11 patients with 75-99% stenosis of the left anterior descending coronary artery (LAD) during coronary artery bypass surgery. Coronary velocities were measured by a 20MHz 80 channel pulsed Doppler velocimeter with a plate type probe. Before indication of extracorporeal circulation, LAD blood velocities were observed at several locations distal to the stenosis. After grafting, velocities in the LAD distal to the graft insertion were measured before and during transient graft occlusion. The waveforms of the poststenotic blood velocity were characterized by systolic peaked flow, and relatively small and fluctuated diastolic flow. The velocity profiles showed irregularity at near the wall immediately distal to the stenosis. A transient graft occlusion caused large reduction in the diastolic peak velocity in the distal native LAD (p<0.01) and an increase in the ratio of the systolic to diastolic velocity (p<0.05). ( J. Jpn. Soc. Biorheol., 2(1), 31~40, 1988).

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To elucidate the role of hemorheological properties of the perfusate in coronary circulation, the diastolic coronary pressure-flow relationships (PFR) were analysed when blood with various hematocrits (Ht; 10-68%) or fluorocarbon emulsion (Fc) was used as perfusate. The left anterior descending and circumflex coronary arteries in open-chest heart-blocked dogs were cannulated with a Y-shaped cannula the other end of which was connected to a pressure controllable reservoir. The coronary vascular bed was maximally dilated with adenosine. Initially, the coronary arteries were perfused with constant pressure from the reservoir which contains blood with certain Ht or Fc. A long diastole was induced by pacing-off and coronary perfusion pressure was decreased rapidly to a preset target pressure. This procedure was repeated changing target pressure at 5 different levels (0-70mmHg). An electrical analog model with proximal resistance R1, capacitance C, distal resistance R2 and back pressure Pb was derived from the observation of the PFR. Estimation of the parameter values was performed so as to fit all pressure-flow data of 5 pairs of experiments by a non-linear optimization method. When the Ht was reduced in 7 dogs, back pressure decreased significantly (r=0.50, p<0.001). The total resistance R1 + R2 and the resistance ratio R2/(R1 + R2) were correlated significantly with Ht (r=0.84 and 0.65). When Fc was used instead of blood in 7 dogs, back pressure and total resistance decreased whereas change in resistance value was not statistically significant. These results demonstrate a significant contribution of hemorheological characteristics of the coronary perfusate to the diastolic coronary artery pressure-flow relationship. (J. Jpn. Soc. Biorheol., 2(1), 41~50, 1988).

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Effect of anions on gel forming ability of κ-carrageenan was studied by dynamic viscoelastic measurement and differential scanning calorimetry. It was found that elastic modulus as a function of salt concentration increased up to a certain salt concentration and then decreased with increasing salt concentration. The maximum value of elastic moduli was found to depend on the balance of the ionic radii of cation and anion of the salt. Temperature dependence of elastic modulus of κ-carrageenan gels containing iode ions showed the anomalous behaviour. Both the endothermic enthalpy and the elastic modulus showed a similar dependence on the salt concentration. The endothermic peak of melting of frozen bound water was found in addition to that of frozen free water for κ-carrageenan gels containing alkali metal salts. The gels containing iode ions showed a different behaviour from those which contain chloride or bromide ions in this case too. (J. Jpn. Soc. Biorheol., 2(1), 51~60, 1988).

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Erythrocyte ghost deformability was measured to study membrane deformability in the absence of the effect of internal viscosity. Human blood was washed with an isotonic Tris-buffered saline and white cells were removed. Ghosts were prepared by lysing red cells in 40 volumes of an ice-cold hypotonic buffer and washing the ghosts three times to yield white ghosts. 10% of volume of a hypertonic Tris-NaC1( 5mM Tris, 1.4M NaCl, pH 7.4) was added to the hypotonic ghost suspension and then incubated at 37°C for one hour to promote resealing.Ghost deformability was measured by laser diffractometry using high refractive arabinogalactan medium. The osmolarity of suspending medium had no effect on the maximum value of the deformability. There was no change in maximum deformability index of ghosts over the pH range of 5.0-9.0. Ghosts showed a progressive loss in deformability with increasing incubation temperature ( 45-50°C for 10 min ). Diamide (1-20 μM) decreased the ghost deformability and dithiotreitol (10mM ) recovered the reduced deformability to original level. These results suggest that the membrane deformability can be measured using ghosts by laser diffractometry. (J. Jpn. Soc. Biorheol., 2(1), 61~67, 1988).

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The retinal traction in rabbits has been measured by Kikkawa et al.. The time elapsed from the onset to the disruption can be obtained. Since the rate of traction is known, the amount of elongation of the chorio-retinal complex up to retinal disruption can be calculated. Qualitatively, the amount of the critical elongation of the chorio-retinal complex up to retinal disruption is larger with a high traction rate than with a low traction rate.
For the above experiments, we have taken the three-element mechanical model. The model is stretched with various traction rates and the relation between the rates and the critical elongation in the model is considered. It is shown that the tendency between the retina and the model is similar.
(J. Jpn. Soc. Biorheol., 2(1), 68~71, 1988).

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