Determination of erythrocyte deformability and its correlation to cellular ATP release using microbore tubing with diameters that approximate resistance vessels in vivo

Abstract

A novel method is described for measuring the deformability of red blood cells (RBCs) in tubing whose diameters approximate forces encountered in vivo. Here, RBCs from rabbits are loaded into a 50 cm section of 75 microm id microbore tubing and connected to a syringe pump. This section of tubing is then connected to a 15 cm section of 25 microm id tubing. As buffer is pumped through the flow system, the RBCs are evacuated from both sections of tubing. However, the inability of the RBCs to move freely through the 25 mirom id section of tubing results in a buildup of cells at the inlet of this portion of tubing. The continued force output by the syringe pump results in a deformation of the RBCs until all of the cells are eventually evacuated from the flow system. It was found that a measurement of the time required to reach half of the maximum pressure (1/2 P(max)) may be used as an indicator of the RBC deformability. For a given sample, a simple buffer results in less time to reach 1/2 P(max) (6.9 +/- 0.2 s) than deformable RBCs (21.6 +/- 0.8 s). To verify that the increased amount of time to reach 1/2 P(max) is indeed due to the RBCs, various hematocrits of an RBC sample were investigated and, as expected, it was found that a 12% RBC hematocrit had a higher 1/2 P(max) value (26.0 s +/- 2.2 s) when compared to a 7% hematocrit (19.1 +/- 0.3 s). In addition, RBCs chemically stiffened with glutaraldehyde were shown to be 25% less deformable than normal RBCs. Finally, a study was performed to examine the relationship between RBC deformability and ATP release and it was found that ATP release increased as a function of RBC deformability. This method greatly simplifies deformability measurements, employing only a syringe pump and microbore tubing, and may lead to a more complete understanding of the physiological significance of erythrocyte deformability.

Red Blood Cell Stimulation of Platelet Nitric Oxide Production Indicated by Quantitative Monitoring of the Communication between Cells in the Bloodstream

“…19 It has also been demonstrated that RBCs release ATP upon mechanical deformation as they traverse microbore tubing 20 or pass through pores that have diameters approximating those of resistance vessels in vivo. 21 The release of ATP from deformed RBCs increases as the tubing or pore diameter decreases.…”

Measurement of purine release with microelectrode biosensors

“…What makes the analysis of blood purines even harder is that red blood cells contain high levels of ATP (1-2 mM, [102]). This can be released in response to hypoxia [103] and cell deformation or damage [104] during sample collection. This means that sample handling of blood for the analysis of purines is of the utmost importance if reliable measurements are to be obtained.…”

Poiseuille Flow of a Non-Local Non-Newtonian Fluid with Wall Slip: A First Step in Modeling Cerebral Microaneurysms

“…We apply the operator J α to (21) and use the following properties of fractional integrals and derivatives [46]:…”

“…In Figure 1, we show a schematic of the structures that are involved in the formation of microaneurysms. A mathematical model capable of predicting the formation, growth and risk of rupture of a microaneurysm needs to incorporate the well-known non-Newtonian behavior of blood when flowing through smaller vessels [21,27,28], the deformability of the vascular wall [29] and relevant mechanotransduction processes taking place among red blood cells, endothelial cells and astrocytes [23,25]. The first step in building such a model is presented in this paper.…”

“…A chemo-mechanical entanglement of blood and endothelial cells at the blood-vascular wall interface that might be caused by a chemical imbalance and/or the forward and backward moving waves reflected from a bifurcation site [20] will cause slip of the blood at the wall. The slip will produce deviations from the expected shear stress level at the wall, which will make the red blood cells release the energy-making enzyme called ATP [21] that will activate a chemical response from the endothelial cells of the wall, which will lastly trigger neuronal-induced release of vasodilators from astrocytes whose endfeet continuously probe and control the amount of mechanical forces on the arterial wall and facilitate complex mechanotransduction processes [22][23][24][25][26]. According to [23,25], the two astrocyte endfeet use Ca 2+ -mediated chemical signals to control vasoconstriction (one endfoot) and vasodilation (the other endfoot).…”