Biorheology - Volume 25, issue 1-2

Authors: Silberberg, A.

Article Type: Research Article

Abstract: Since the work of Bundgaard it is known that the interendothelial cell cleft is a narrow, but open, sometimes highly convoluted gap linking the blood vessel lumen with the subendothelial space. A remarkable feature of this cleft is its constant width. It is here suggested that electrostatic repulsions, and the presence of a system of posts between the walls act to maintain cleft width. Contrary to intuition the presence of posts would not constitute an intolerable increase in hydrodynamic resistance, since no massive posts are necessary. Links between the walls involving only a single macromolecular chain each, which would be …very difficult to detect ultrastructurally, would, nevertheless, particularly when charged, act as extremely stiff springs of essentially fixed length. A detailed calculation is presented to show how this idea could work and it is proposed that similar such posts support the subendothelial layers. Recent ultrastructural evidence in support of single chain links is quoted. Show more

Keywords: Transvascular wall transport, interendothelial cleft, capillary permeability, extravascular circulation, lymph formation

DOI: 10.3233/BIR-1988-251-240

Citation: Biorheology, vol. 25, no. 1-2, pp. 303-318, 1988

Authors: Ninomiya, M. | Fujii, M. | Niwa, M. | Sakamoto, K. | Kanai, H.

Article Type: Research Article

Abstract: The changes of viscosity, optical reflection and electrical resistivity of blood due to flow are dependent on the orientation and deformation of red cells. From electrical point of view, it can be assumed that blood is suspension of small insulating particles (red cells) in conductive fluid (plasma) when the frequency of supplied voltage is lower than several hundreds KHz. When blood flows, red cells deform and orient in flow direction. Therefore, flowing blood shows anisotropic electrical and optical properties. In steady flow, blood resistivity longitudinal to flow decrease with flow rate, and transverse one increases. Blood flow in living body …is not steady but pulsatile. We measured both longitudinal and transverse resistivity changes, optical reflection change and viscosity change of sinusoidally flowing blood in a rectangular conduit. The results are 1) during one period of sinusoidal flow the longitudinal resistivity change is opposite to that of transverse one, 2) the waveform of reflection light change is similar to that of resistance change, and 3) minimum points of both longitudinal resistivity and viscosity changes do not appear at the moment when flow is zero but are delayed. When the amplitude of sinusoidal flow is small and oscillation frequency is high, the phase difference between the zero crossing period of flow and the period of minimum change in resistivity, increases up to 90°. Viscosity of blood decreases with increase of amplitude and frequency of sinusoidal flow. Show more

Keywords: deformation, orientation, electrical resistivity, viscosity, optical reflection

DOI: 10.3233/BIR-1988-251-241

Citation: Biorheology, vol. 25, no. 1-2, pp. 319-328, 1988

Authors: Asano, M. | Ohkubo, C. | Hirokawa, A. | Sasaki, A. | Tochihara, Y. | Chiba, Y.

Article Type: Research Article

Abstract: In normal male rabbits loaded dietary cholesterol, intravital-microscopy revealed a marked acceleration of intravascular adhesiveness of white blood cells and aggregability of red blood cells and a swarming of lipid-laden macrophages in connective tissue space concurrently with a systemic hyperlipidemia and anemia. Possible roles of the microcirculatory changes in the atherogenesis were discussed.

Keywords: atherogenesis, cholesterol feeding, CO inhalation, intravital-microscopy, rabbit ear chamber

DOI: 10.3233/BIR-1988-251-242

Citation: Biorheology, vol. 25, no. 1-2, pp. 329-338, 1988

Authors: Ohshima, Norio | Sato, Masaaki | Oda, Naohito

Article Type: Research Article

Abstract: Velocities of the red blood cell (RBC) and the suspending medium in glass capillaries of 9 to 20 μ m were measured under microscopic observation. The effects of physical factors such as driving pressure, capillary diameter, hematocrits and RBC deformability on flow velocities were studied using freshly drawn blood of the rat resuspended in phosphate buffered saline solution in the hematocrit range between 5 and 12.5 %. These RBC suspensions were made to flow through the test glass capillaries under known negative driving pressures. Ratios of capillary hematocrit to feed hematocrit taken as measures of the Fahraeus effect showed almost …constant value of about 0.74. While, ratios of capillary hematocrit to discharge hematocrit showed a characteristic dependence on capillary diameter, showing minimal values at about 13 μ m in capillary diameter. The same hematocrit ratios were found to be well correlated with values of wall shear rates estimated from the relative RBC velocities. Show more

Keywords: microhemodynamics, Fahraeus effect, glass capillary, hemorheology, hematocrit, deformability

DOI: 10.3233/BIR-1988-251-243

Citation: Biorheology, vol. 25, no. 1-2, pp. 339-348, 1988

Authors: Lacombe, C. | Bucherer, C. | Ladjouzi, J. | Lelièvre, J.C.

Article Type: Research Article

Abstract: Plasmatic proteins, namely fibrinogen and globulins, play a major role in red blood cell (RBC) aggregation which is accountable for the three-dimensional structure of blood. Consequently, blood rheological properties linked to this structure must be modified when the protein plasma content changes. This paper gives results and related comments on thixotropic properties of RBC suspensions (0.45 hematocrit) in isotonic solutions containing various amount of fibrinogen to which albumin is added. Thixotropic behavior of these RBC suspensions is studied with a low inertia coaxial cylinders viscometer at a shear rate step of γ ˙ = 1 s − …1 Rheograms are interpreted in term of thixotropy coefficient. The main conclusion is that albumin improves RBC disaggregability of whole blood, resulting probably from a competitive effect between fibrinogen and albumin in the RBC aggregation process. Show more

Keywords: Blood thixotropy, Red blood cell aggregation, Fibrinogen, Albumin

DOI: 10.3233/BIR-1988-251-244

Citation: Biorheology, vol. 25, no. 1-2, pp. 349-354, 1988

Authors: Schmid-Schönbein, H.

Article Type: Research Article

Abstract: Red cell aggregate sedimentation under gravitation produces pronounced and rapid “phase separation effects” culminating in “compaction stasis” (CS), i.e. almost complete stuffing of microvessels by RBC. This can be readily observed and monitored in microvessels of vertically placed mesentery preparations by a horizontally aimed intravital microscope as shown by (Göbel et al. Virchow’s Arch., 1988,). “Layered flow”, floatational plasma skimming and progressive increase in local tube hematocrit (HT) up to 100% (“compaction stasis”) occurs during induced low flow states in vivo (here preferentially in postcapillary venules), as well as in vitro (non-permeable artificial micro tube networks). Quantitative densitometry …and velocimetry in vertically placed microvessels demonstrates that the process of RCA sedimentation results in progressive vertical skewing of the velocity profile, culminating in standstill of the RBC-sediment in the dependent vessel half, with superfluent plasma and small aggregates in the upper vessel half. The theory of compaction stasis is developed: in striking contrast to the situation under high shear conditions, red cells travel on slower trajectories than plasma: due to “red cell undervelocity” the average residence times of RBC in a venule is much higher than that of plasma. Consequently, CS can be explained as the result of a Fahraeus effect reversal since the principle of mass conservation requires that HT » HD. Network aspects and hemodynamic consequences are also incorporated into the theory. Show more

Keywords: erythrocyte aggregation, Fahraeus-Effect, discharge hematocrit, intravascular sedimentation, plasma skimming, post-capillary resistance, stasis, tube hematocrit

DOI: 10.3233/BIR-1988-251-245

Citation: Biorheology, vol. 25, no. 1-2, pp. 355-366, 1988

Authors: Donner, M. | Siadat, M. | Stoltz, J.F.

Article Type: Research Article

Abstract: Erythro-aggregometer is a Couette viscometer which was developed to measure aggregation parameters of red blood cells. The system is based on the analysis of the light intensity backscattered by a blood suspension. It allows to approach aggregation phenomenon in terms of kinetics, structural and rheological parameters. The measurement system designed for use with a microcomputer is suitable for both research and clinical investigations.

Keywords: Red blood cells, aggregation, back-scattered light

DOI: 10.3233/BIR-1988-251-246

Citation: Biorheology, vol. 25, no. 1-2, pp. 367-376, 1988

Authors: Copley, Alfred L.

Article Type: Research Article

Keywords: Anticoagulant, atherogenesis, atheroma, antithrombotic agents, basement membrane, cement fibrin(ogenin), Copley-Scott Blair phenomenon, endoendothelial fibrin(ogenin) lining (EEFL), Fåhraeus-Lindqvist phenomenon, fibrin, fibronectin, fibrinogenin, fibrino(geno)lysis, freeze etching, gel pore size, hemorrhagic conditions, hemostasis, hyperthermia cancer therapy, inflammation, inter-endothelial junction, leukocyte emigration, main filtration barrier, microcirculation, pathophysiology, perihemorheology, plasmatic zone, protein leakage, pseudo-hemorrhage, thrombogenesis, thrombosis, transcapillary transport, vascular patency, vessel-blood organ, vessel elasticity

DOI: 10.3233/BIR-1988-251-247

Citation: Biorheology, vol. 25, no. 1-2, pp. 377-399, 1988

Article Type: Other

DOI: 10.3233/BIR-1988-251-248

Citation: Biorheology, vol. 25, no. 1-2, pp. 401-401, 1988