Equilibrium shapes of red blood cells in osmotic swelling

Pai, Bipin K.; Weymann, Helmut D.

doi:10.1016/0021-9290(80)90184-0

Cited by 18 publications

(16 citation statements)

References 14 publications

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“…3. We assume that the RBC is at mechanical equilibrium at all times, allowing us to neglect inertia [58][59][60]. This assumption is consistent with the experimentally observed shapes for the resting RBCs in both vivo and vitro [61,62].…”

Section: Assumptionssupporting

confidence: 60%

Non-uniform distribution of myosin-mediated forces governs red blood cell membrane curvature through tension modulation

et al. 2020

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The biconcave disk shape of the mammalian red blood cell (RBC) is unique to the RBC and is vital for its circulatory function. Due to the absence of a transcellular cytoskeleton, RBC shape is determined by the membrane skeleton, a network of actin filaments cross-linked by spectrin and attached to membrane proteins. While the physical properties of a uniformly distributed actin network interacting with the lipid bilayer membrane have been assumed to control RBC shape, recent experiments reveal that RBC biconcave shape also depends on the contractile activity of nonmuscle myosin IIA (NMIIA) motor proteins. Here, we use the classical Helfrich-Canham model for the RBC membrane to test the role of heterogeneous force distributions along the membrane and mimic the contractile activity of sparsely distributed NMIIA filaments. By incorporating this additional contribution to the Helfrich-Canham energy, we find that the RBC biconcave shape depends on the ratio of forces per unit volume in the dimple and rim regions of the RBC. Experimental measurements of NMIIA densities at the dimple and rim validate our prediction that (a) membrane forces must be nonuniform along the RBC membrane and (b) the force density must be larger in the dimple than the rim to produce the observed membrane curvatures. Furthermore, we predict that RBC membrane tension and the orientation of the applied forces play important roles in regulating this force-shape landscape. Our findings of heterogeneous force distributions on the plasma membrane for RBC shape maintenance may also have implications for shape maintenance in different cell types.

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Section: Assumptionssupporting

confidence: 60%

Non-uniform distribution of myosin-mediated forces governs red blood cell membrane curvature through tension modulation

et al. 2020

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“…However, when the erythrocytes reach a near-spherical shape and exceed max / V V = 0.88, the strain energy caused due to shearing increases rapidly and becomes larger than that caused due to bending. This tendency is similar to that of the literature (Pai, et al, 1980). The shape of the erythrocyte at the near-spherical shape in the swelling process of erythrocytes, it is necessary to consider the shear rigidity.…”

Section: Validation Of Methodssupporting

confidence: 88%

“…Therefore, to evaluate these values, it is necessary to observe the swelling process until the spherical shape is obtained. In order to analyze the swelling process, this study employs the method of minimizing strain energy that requires numerical calculation (Zarda, et al, 1977;Pai, et al, 1980;Fischer, et al, 1981). First, to examine the validity of the calculation method, we compared the results with the calculation results of the solution method of erythrocyte swelling that involves considering the differential equation as the governing equation (Pozrikidis, 2003), and with the results of an experiment that involves application of osmotic shock to the erythrocytes (Bando, et al, 2020).…”

Section: Effects Of Rigidity On Tension Within the Cell Membranes Of Erythrocytes Swollen By Osmotic Shockmentioning

confidence: 99%

Effects of rigidity on tension within the cell membranes of erythrocytes swollen by osmotic shock

Bando

Otomo

2022

JBSE

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Erythrocytes swell owing to the osmotic shock caused by hypotonic liquids, and when the membrane tension exceeds a certain limit, hemolysis occurs. The base tension in the membrane of a spherically shaped erythrocyte is usually ignored in the mechanical evaluation of hemolysis. However, the base tension cannot be ignored when the rigidity of the erythrocyte membrane increases owing to lesions, oxidative stress, and other phenomena. Therefore, it is necessary to re-evaluate the tension level at which hemolysis occurs by considering the increased base tension, which is caused by a combined increase in the bending and shear rigidity of the membrane. To achieve this, we calculated the effect of increases in the combined rigidity on the increases in the internal pressure and membrane tension of the erythrocyte. In this study, assuming the surface area to be constant, the swelling process of erythrocytes was evaluated under the condition that hemolysis does not occur. Evaluation was performed by minimizing strain energy, which is the sum of bending strain and shear strain. When the erythrocyte was spherical, the membrane base tension increased linearly with combined rigidity. Even when the bending rigidity was increased to 100 times that of normal erythrocytes, the effect of the base tension on the hemolysis tension level (15 mN/m) was negligible. However, when shear rigidity was increased to 50-100 times that of normal erythrocytes, it became necessary to decrease the hemolysis tension level by 10% and 20%, respectively, because the base tensions were approximately 1.5 and 3.0 mN/m, respectively.

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“…3. We assume that the RBC is at mechanical equilibrium at all time scales, allowing us to neglect inertia [52][53][54] . This assumption is consistent with the experimentally observed shapes for the resting RBCs in both vivo and vitro [55,56] .…”

Section: 1-assumptionsmentioning

confidence: 99%

Non-uniform distribution of myosin-mediated forces governs red blood cell membrane curvature through tension modulation

Alimohamadi

Smith

Nowak

et al. 2019

Preprint

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The biconcave disk shape of the mammalian red blood cell (RBC) is unique to the RBC and is vital for its circulatory function. Due to the absence of a transcellular cytoskeleton, RBC shape is determined by the membrane skeleton, a network of actin filaments cross-linked by spectrin and attached to membrane proteins. While the physical properties of a uniformly distributed actin network interacting with the lipid bilayer membrane have been assumed to control RBC shape, recent experiments reveal that RBC biconcave shape also depends on the contractile activity of nonmuscle myosin IIA (NMIIA) motor proteins. Here, we use the classical Helfrich-Canham model for the RBC membrane to test the role of heterogeneous force distributions along the membrane and mimic the contractile activity of sparsely distributed NMIIA filaments. By incorporating this additional contribution to the Helfrich-Canham energy, we find that the RBC biconcave shape depends on the ratio of forces per unit volume in the dimple and rim regions of the RBC. Experimental measurements of NMIIA densities at the dimple and rim validate our prediction that (a) membrane forces must be non-uniform along the RBC membrane and (b) the force density must be larger in the dimple than the rim to produce the observed membrane curvatures. Furthermore, we predict that RBC membrane tension and the orientation of the applied forces play important roles in regulating this force-shape landscape. Our findings of heterogeneous force distributions on the plasma membrane for RBC shape maintenance may also have implications for shape maintenance in different cell types.

show abstract

Equilibrium shapes of red blood cells in osmotic swelling

Cited by 18 publications

References 14 publications

Non-uniform distribution of myosin-mediated forces governs red blood cell membrane curvature through tension modulation

Non-uniform distribution of myosin-mediated forces governs red blood cell membrane curvature through tension modulation

Effects of rigidity on tension within the cell membranes of erythrocytes swollen by osmotic shock

Non-uniform distribution of myosin-mediated forces governs red blood cell membrane curvature through tension modulation

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