Effect of thrombocytapheresis on blood rheology in healthy donors: role of nitric oxide.

Platelet transfusions are increasingly being used to treat thrombocytopenic conditions. Because of anticoagulation, changes in blood composition and extracorporeal circulation, donor apheresis may cause alterations in hemorheology. This study aimed at investigating the effects of thrombocytapheresis on donor blood rheology. The effect of nitric oxide (NO) on donor red blood cell (RBC) deformability after thrombocytapheresis was also studied. Platelets were collected by a Haemonetics MCS 3p cell seperator. Blood samples were obtained before and 15 min after thrombocytapheresis. RBC deformability and aggregation were measured using an ektacytometer, whole blood viscosity (WBV) was determined with a cone-plate rotational viscometer. Donor RBCs were shown to be less deformable at all stress levels except 0.30 Pa after thrombocytapheresis and NO donor sodium nitroprusside (SNP, 10(-6) M) reversed the reduced deformability caused by thrombocytapheresis. It was observed that donor apheresis induces a decrement in RBC aggregation and WBV measured at standard hematocrit (Hct). No significant alterations were observed in WBV values determined at native Hct values. Thrombocytapheresis also resulted in a decrement in fibrinogen, total protein, cholesterol and albumin levels whereas Hct was found to be increased and serum glucose, triglyceride, hemoglobin levels unaltered after apheresis. These results suggest that, thrombocytapheresis causes alterations in hemorheological parameters and hence in the perfusion of the microvasculature of the donors and NO appears to have a protective effect on the impairment observed in RBC deformability.