Platelet aggregatory responses to low-dose collagen are maintained in hirudin-anticoagulated whole blood for 24 h when stored at room temperature.
Whole blood from 15 volunteers was anticoagulated with hirudin (200U/l) and the response to a known submaximal concentration of collagen (0.6 microg/ml) was tested by impedance aggregometry. In 8 volunteers platelet counts were also taken before and after the maximum aggregatory response. These tests were repeated when the samples had rested for 24 h at room temperature. The median [interquartile range] aggregatory response immediately after sampling was 17.3 [16.7-18.4] ohms. At 24 h it was 17.7 [15.8-19.3] ohms (p = 0.88) although variance was increased (p = 0.006). The immediate platelet count before collagen exposure was 438 [381-510] x 10(9)/l and 258 [227-297] x 10(9)/l post-collagen. At 24 h the platelet count was 448 [443-473] x 10(9)/l (p = 0.224 versus immediate count) but variance was not increased (p = 0.215). After full aggregation the count fell to 284 [234-304] x 10(9)/l (p = 0.592 versus early post-collagen). Variances were similar (p = 0.558). Aggregate response ratios increased non-significantly after 24 h from 0.59 [0.53-0.62] to 0.64 [0.51-0.68] although variance was increased (p = 0.021). Full macroaggregatory responses by impedance aggregometry were seen after 24h storage of whole blood with hirudin at room temperature. This suggests both that distant assessment of platelet function using a standardized method is possible and a potential role of thrombin inhibition for platelet storage.
Belcher
P R
PR
University of Glasgow, Department of Cardiac Surgery, Royal Infirmary, UK. pbelcher@clinmed.gla.ac.uk
Muriithi
E W
EW
Day
S P
SP
Wheatley
D J
DJ
D000925:Anticoagulants / Q000097:blood / Q000494:pharmacology; D001793:Blood Preservation; D003094:Collagen / Q000494:pharmacology*; D006629:Hirudins / Q000097:blood / Q000494:pharmacology; D006801:Humans; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects*; D010976:Platelet Count; D010979:Platelet Function Tests; D013696:Temperature; D013997:Time Factors
D000925:Anticoagulants; D006629:Hirudins; D003094:Collagen