Red Blood Cell Mechanics and Functional Capillary Density

1995 ◽  
Vol 15 (5) ◽  
pp. 250-254 ◽  
Author(s):  
T.W. Secomb ◽  
R. Hsu
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Cell Mechanics ◽  
Capillary Density ◽  
Functional Capillary Density

Effect of erythrocyte aggregation at normal human levels on functional capillary density in rat spinotrapezius muscle

2006 ◽  
Vol 290 (3) ◽  
pp. H941-H947 ◽  
Author(s):  
Sangho Kim ◽  
Aleksander S. Popel ◽  
Marcos Intaglietta ◽  
Paul C. Johnson
Keyword(s):  
Arterial Pressure ◽  
Blood Cell ◽  
Red Blood Cell ◽  
High Speed ◽  
Capillary Density ◽  
Functional Capillary Density ◽  
Erythrocyte Aggregation ◽  
Reduced Pressure ◽  
Healthy Humans ◽  
Plasma Skimming

Previous studies have shown that functional capillary density (FCD) is substantially reduced by erythrocyte aggregation. However, only supranormal levels of aggregability were studied. To investigate the effect of erythrocyte aggregability at the level seen in healthy humans, the FCD of selected capillary fields in rat spinotrapezius muscle was determined with high-speed video microscopy under normal (nonaggregating) conditions and after induction of erythrocyte aggregation with Dextran 500 (200 mg/kg). To examine shear rate dependence, the effect was studied both at normal and reduced arterial pressures (50 and 25 mmHg), the latter achieved by short periods of hemorrhage. In a separate study, volume flow was determined in arterioles (52.1 ± 3.7 μm) under the same conditions. Before Dextran 500 infusion, FCD fell to 91% and 76% of control values, respectively, when arterial pressure was reduced to 50 and 25 mmHg. After Dextran 500 infusion, FCD was 96% at normal arterial pressure and fell to 79% and 37% of normal control values at 50 and 25 mmHg. All FCD values were significantly lower after dextran infusion. FCD reduction after lowering arterial pressure or dextran infusion appeared to be due to plasma skimming rather than capillary plugging. Reduction of FCD by dextran at reduced pressure was compensated by increased red blood cell flux in capillaries with red blood cell flow. We conclude that the level of aggregability seen in healthy humans is an important determinant of FCD only at reduced arterial pressure.

A Fluid Structure Interaction Model for the Red Blood Cell Mechanics

2016 ◽  
Vol 5 (6) ◽  
pp. 524-528
Author(s):  
Alireza Karimi ◽  
Kamran Hassani ◽  
Ali Tavakoli Golpaygani ◽  
Farhad Izadi
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Cell Mechanics ◽  
Fluid Structure Interaction ◽  
Interaction Model ◽  
Fluid Structure ◽  
Structure Interaction

Hemorrhagic hypotension induces arteriolar vasomotion and intermittent capillary perfusion in rat pancreas

1994 ◽  
Vol 267 (5) ◽  
pp. H1936-H1940 ◽  
Author(s):  
B. Vollmar ◽  
G. Preissler ◽  
M. D. Menger
Keyword(s):  
Blood Cell ◽  
Microscopic Analysis ◽  
Capillary Density ◽  
Functional Capillary Density ◽  
Intravital Fluorescence Microscopy ◽  
Capillary Perfusion ◽  
Induced Hypotension ◽  
Rat Pancreas ◽  
Hemorrhagic Hypotension ◽  
Acinar Tissue

Hemorrhage-induced intermittent capillary perfusion and its relation to arteriolar vasomotion was studied in rat pancreatic acinar tissue using intravital fluorescence microscopy. During prehemorrhage conditions, microscopic analysis of the pancreatic microcirculation displayed neither arteriolar vasomotion nor intermittency of capillary perfusion (n = 22 animals). Hemorrhage-induced hypotension of 40 mmHg provoked arteriolar vasomotion in 18 of 22 animals and 59 of 115 arterioles studied. The maximum relative amplitude of arteriolar vasomotion was 44 +/- 8% (range 12–81%), and vasomotion frequency averaged 4.73 +/- 0.11 cycles/min. Hemorrhagic hypotension was further accompanied by 1) a decrease of functional capillary density [length of red blood cell-perfused capillaries per area of tissue under investigation (cm/cm2)] from 515 +/- 3 cm-1 at baseline to 386 +/- 3 cm-1 (P < 0.05) and 2) the instantaneous occurrence of intermittency of capillary perfusion in all observation areas (N = 220) of the 22 animals studied. The frequency of intermittency of capillary perfusion (4.72 +/- 0.14 cycles/min) did not differ from the frequency of arteriolar vasomotion, which implies a causal relationship between these two hemorrhage-induced microvascular mechanisms with the probable aim to counteract the decrease of functional capillary density.

Microvascular responses to hemodilution with Hb vesicles as red blood cell substitutes: influence of O2 affinity

1999 ◽  
Vol 276 (2) ◽  
pp. H553-H562 ◽  
Author(s):  
Hiromi Sakai ◽  
Amy G. Tsai ◽  
Ronald J. Rohlfs ◽  
Hiroyuki Hara ◽  
Shinji Takeoka ◽  
...  
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Carrying Capacity ◽  
Capillary Density ◽  
Microvascular Perfusion ◽  
Phospholipid Vesicles ◽  
Molar Ratios ◽  
Allosteric Effector ◽  
Syrian Golden Hamsters ◽  
Optimal Value

Phospholipid vesicles encapsulating purified hemoglobin (HbV) were developed to provide O2-carrying capacity to plasma expanders. Microvascular perfusion was determined for HbV with different O2 affinity (P50 = 9, 16, and 30 mmHg) prepared by coencapsulating pyridoxal 5′-phosphate (PLP) at the molar ratios of [PLP]/[Hb] = 0, 0.5, and 3, respectively (cf. hamster blood, P50: 28 mmHg), and suspended in 8 g/dl human serum albumin (HSA). Eighty percent of the red blood cell (RBC) mass of conscious Syrian golden hamsters fitted with dorsal skinfold windows was substituted with either of the HbV-HSA suspensions, washed hamster RBC suspended in HSA (RBC-HSA), and HSA alone. All three HbV-HSA groups and RBC-HSA groups showed stable blood pressure and heart rate, which could not be sustained with HSA alone. Only the HbV (P50 = 9)-HSA group showed an increase in arterial O2tension (89.8 ± 14.7 mmHg, baseline 58.4 ± 4.0 mmHg) because of hyperventilation, and microvascular perfusion was decreased, indicating that facilitated O2 unloading of HbV by decreasing the O2 affinity (increasing P50) with PLP as an allosteric effector is important. Microvascular perfusion and microvascular and interstitial O2tensions in the HbV (P50 = 16 and 30)-HSA groups were significantly higher than those in the HSA group. The O2 release rate from the HbV was 18–32 s−1 vs. 4.4 s−1 for RBC. Functional capillary density was improved from 17 to 41% on average by decreasing P50 from 30 to 16 mmHg, which appears to be an optimal value for the P50 in this system.

scholarly journals Measurement of red blood cell mechanics during morphological changes

2010 ◽  
Vol 107 (15) ◽  
pp. 6731-6736 ◽  
Author(s):  
Y. Park ◽  
C. A. Best ◽  
K. Badizadegan ◽  
R. R. Dasari ◽  
M. S. Feld ◽  
...  
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Cell Mechanics ◽  
Morphological Changes

Targeted O2 delivery by low-P50 hemoglobin: a new basis for O2 therapeutics

2003 ◽  
Vol 285 (4) ◽  
pp. H1411-H1419 ◽  
Author(s):  
Amy G. Tsai ◽  
Kim D. Vandegriff ◽  
Marcos Intaglietta ◽  
Robert M. Winslow
Keyword(s):  
Blood Cell ◽  
Red Blood Cells ◽  
Red Blood Cell ◽  
Blood Cells ◽  
Capillary Density ◽  
Bovine Hemoglobin ◽  
Free Hemoglobin ◽  
Plasma Hemoglobin ◽  
Arterial Blood ◽  
Surface Modified

To assess O2 delivery to tissue by a new surface-modified, polyethylene glycol-conjugated human hemoglobin [MP4; Po2 at 50% saturation of hemoglobin (P50); 5.4 mmHg], we studied microcirculatory hemodynamics and O2 release in golden Syrian hamsters hemodiluted with MP4 or polymerized bovine hemoglobin (PolyBvHb; P50 54.2 mmHg). Comparisons were made with the animals' hemodiluted blood with a non-O2 carrying plasma expander with similar solution properties (Dextran-70). Systemic hemodynamics (arterial blood pressure and heart rate) and acid-base parameters were not correlated with microhemodynamics (arteriolar and venular diameter, red blood cell velocity, and flow). Microscopic measurements of Po2 and the O2 equilibrium curves permitted analysis of O2 release in precapillary and capillary vessels by red blood cells and plasma hemoglobin separately. No significant differences between the groups of animals with respect to arteriolar diameter, flow, or flow velocity were observed, but the functional capillary density was significantly higher in the MP4-treated animals (67%) compared with PolyBvHb-treated animals (37%; P < 0.05) or dextran-treated animals (53%). In the PolyBvHb-treated animals, predominant O2 release (both red blood cells and plasma hemoglobin) occurred in precapillary vessels, whereas in MP4 animals most of the O2 was released from both red blood cells and plasma hemoglobin in capillaries. Base excess correlated directly with capillary O2 release but not systemic O2 content or total O2 release. Higher O2 extraction of both red blood cell and plasma hemoglobin in capillaries represents a new mechanism of action of cell-free hemoglobin. High O2 affinity appears to be an important property for cell-free hemoglobin solutions.

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