Red blood cell aggregability is increased by aspirin and flow stress, whereas dipyridamole induces cell shape alterations: measurements by digital image analysis

Abstract

We evaluated the influence of pretreatment with aspirin in vitro, alone or combined with dipyridamole, on red cell aggregability. Samples were tested before and after being exposed to well-defined flow conditions. An aggregation rate was estimated through digital analysis of light microscopy images. Red cells of untreated blood that had been exposed to flow showed a higher aggregation rate (38.54 +/- 1.63 vs. 27.52 +/- 1.36; P < 0.05). This effect was not observed in the absence of platelets. Treatment with aspirin induced a high aggregation rate, with or without exposure to flow conditions. Dipyridamole alone or combined with aspirin provoked echinocytosis, disturbing the rouleaux arrangement (rates ranging from 11.25 +/- 1.91 - 13.62 +/- 1.62). Washing red cells after treatment restored about 90% of echinocytes to their biconcave shape, but aggregation rate did not recover in parallel. These results highlight the influence of red cell-platelet interactions in the regulation of haemostasis and show how therapeutic agents can interfere with rheological phenomena.

The Effect of Anti-Platelet Aggregation to Prevent Pressure Ulcer Development: A Retrospective Study of 132 Elderly Patients

“…In our study, 8 of 9 patients (88.9%) were not prescribed any other anti-platelet aggregation drugs except NSAIDs in the group with pressure ulcers, whereas 5 of 10 patients (50.0%) treated with NSAIDs had been given another anti-platelet aggregation medicine in the group without pressure ulcers (data not shown). This finding may support a previous report that aspirin did not exert its pharmacological effect of suppressing platelet aggregation by inhibiting cyclooxygenase under high shear-stress conditions in arterioles [18,31]. Our failure to show a significant difference in the frequency of NSAIDs including aspirin medication may relate to the lack of power in the analysis because of the limited number of patients in the study; therefore similar prospective studies are needed to ascertain whether our result is reproducible.…”

“…We did this by investigating their medical records retrospectively. While some case-controlled trials revealed that anti-platelet aggregation therapy had pre-Matsuyama/Takano/Miura/Yamamoto/ Mashiko/Ohotani dominant effects on primary and secondary prevention for cerebrovascular and coronary diseases [18,[28][29][30], little is known of its efficacy for the prevention of pressure ulcers. Our retrospective data suggest for the first time the efficacy of anti-platelet aggregation therapy for preventing pressure ulcer formation in bedridden elderly patients following acute inflammatory diseses.…”

“…The frequency of NSAIDs including aspirin medication was higher in the patients with pressure ulcers than without. In an in vitro red blood cell aggregation study of hemorheological phenomena, red cells treated with aspirin showed a high aggregation rate after exposure to well-defined flow conditions, but aspirin combined with dipyridamole provoked echinocytosis, disturbing the rouleau arrangement [18]. In our study, 8 of 9 patients (88.9%) were not prescribed any other anti-platelet aggregation drugs except NSAIDs in the group with pressure ulcers, whereas 5 of 10 patients (50.0%) treated with NSAIDs had been given another anti-platelet aggregation medicine in the group without pressure ulcers (data not shown).…”

“…We defined the drugs (ticlopidine, dipyridamole, aspirin, and other NSAIDs including indomethacin, diclofenac sodium, and mefenamic acid) as mediators of anti-platelet aggregation in this study. Because each of these drugs is classified according to differential pharmacological effects in reducing aggregation activity [17][18][19][20], an elderly patient taking more than two was assessed in each drug group. Patients who had not taken a therapeutic dose of the drug or not been prescribed it for more than 7 days before becoming bedridden were not eligible.…”

Quantitative Measurement and Evaluation of Red Blood Cell Aggregation in Normal Blood Based on a Modified Hanai Equation

“…Among the biophysical properties of blood, RBC aggregation is the major cause of the non-Newton flow properties of whole blood, and it has been popularly utilized to diagnose the inflammatory diseases in clinic, since the level of aggregation rises enormously in association with diabetes [18], sepsis [19], myocardial ischaemia [20] and so on. Up to now, various researchers have paid attention to the measurement of RBC aggregation, and some novel techniques based on laser backscattering [21,22], microscopic counter [23,24], ultrasound backscattering [25,26,27] and electrical impedance spectroscopy [28,29] have been developed and described.…”