Experimental investigation of the rheological activation of blood platelets

Abstract

In order to define various aspects of platelet rheological activation, samples of whole blood and platelet-rich plasma (PRP) from the same donors were subjected for 5 min to shear rates increasing from 10 to 10000 sec⁻¹ (shear stresses from 10⁻² to 30 Pa approximatively) in a Couette type viscometer. The following parameters were measured: erythrocyte hemolysis; lactic dehydrogenase activity; plasma B-Thromboglobulin(B-TG); adenine nucleotides, and platelet photometric aggregation. The experimental results reveal that:

In whole blood, hemolysis only reached at maximum 2% of the total hemolysis. Plasma LDH activity increased regularly beyond 500 sec⁻¹, in close correlation with B-TG plasma concentration. In contrast, ADP and ATP levels remained stable up to 1000 sec⁻¹ then increased slowly. In PRP, the LDH, ADP and ATP levels remain practically stable up to shear rates around 5000 sec⁻¹. In contrast, B-TG appeared to be released in plasma at shear rate values of 3000 sec⁻¹ and its progression is only correlated with the other parameters, when the platelet lysis occurred. Finally, a rapid and complete inhibition of platelet aggregation to ADP was observed from 5000 sec⁻¹.