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Role of protein adsorption in micropore passability of red blood cells
Abstract:
Micropore passability of fresh human blood was measured by means of an improved Nuclepore membrane filter method under varying concentrations of electrolytes and proteins in the plasma. The method gives an average pore passage time required for single red blood cells to flow through 5 micrometers pores of the filter membrane. Micropore passability is reduced with increasing ionic osmolarity above 320 mOsM when the protein concentration is normal However, it remains constant up to 370 and 430 mOsM when the protein concentration is lowered to 1/3 and 1/6 of normal, respectively. Furthermore, when red blood cells are added to an hyperosmotic plasma, the protein concentration detectable in the plasma is reduced to a level lower than expected from a simple osmotic water shift. The excess reduction in the protein concentration is nearly proportional to the amount of added red blood cells. The following succession of events was assumed in order to interpret these results. An electric repulsive force between red blood cells and plasma proteins is weakened by an increased ion concentration. This reduction in this repulsive force will increase the adsorption of proteins on the surfaces of the red blood cells. The adsorbed proteins will restrict cell membrane flexibility, causing a reduced micropore passability of red blood cells.
Insights
Red blood cell micropore passability decreases with higher salt concentrations. Adding red blood cells to hyperosmotic plasma reduces detectable protein levels, suggesting protein adsorption to cells impacts their flexibility and flow.
Area of Science:
- Hematology
- Biophysics
- Biochemistry
Background:
- Red blood cell (RBC) deformability is crucial for microcirculation.
- Plasma composition, including electrolytes and proteins, influences RBC behavior.
- Understanding factors affecting RBC passage through narrow pores is vital for diagnosing blood disorders.
Purpose of the Study:
- To investigate the impact of varying electrolyte and protein concentrations on human blood micropore passability.
- To elucidate the mechanisms behind reduced RBC flow in hyperosmotic conditions.
Main Methods:
- Utilized an improved Nuclepore membrane filter method to measure RBC passage time through 5 micrometer pores.
- Systematically altered plasma electrolyte osmolarity and protein concentrations.
- Quantified protein concentration changes in plasma after RBC addition.
Main Results:
- Micropore passability significantly decreased with increasing ionic osmolarity (>320 mOsM) at normal protein levels.
- RBC passability remained constant up to higher osmolarities (370-430 mOsM) when protein concentrations were reduced.
- Hyperosmotic plasma with added RBCs showed a greater-than-expected decrease in detectable protein, proportional to RBC volume.
Conclusions:
- Increased ion concentration weakens repulsive forces between RBCs and plasma proteins, promoting protein adsorption.
- Adsorbed proteins reduce RBC membrane flexibility, impairing micropore passability.
- Plasma protein levels and ionic osmolarity interact to critically affect RBC deformability and microcirculatory function.