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Increased platelet aggregation due to chilling to 20 degrees C is not related to increased sensitivity to agonists
Author(s) -
Hansen Thomas N.,
Brockbank Kelvin G.M.
Publication year - 1997
Publication title -
transfusion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.045
H-Index - 132
eISSN - 1537-2995
pISSN - 0041-1132
DOI - 10.1046/j.1537-2995.1997.37797369444.x
Subject(s) - platelet , arachidonic acid , agonist , chemistry , thromboxane a2 , thromboxane , ed50 , adenosine diphosphate , platelet aggregation , dense granule , biochemistry , biophysics , medicine , enzyme , in vitro , receptor , biology
BACKGROUND: Previous studies suggested that chilled platelets have a greater sensitivity to agonists than do platelets aggregated at 37 degrees C. STUDY DESIGN AND METHODS: Washed platelets were aggregated at 20 or 37 degrees C with ADP (0‐20 microM), arachidonic acid (0‐200 microM), or the thromboxane mimetic U46619 (0‐9 nM). RESULTS: Chilling caused a significant (p < or=0.05) increase in spontaneous platelet aggregation (> 27% at 20 degrees C vs < 5% at 37 degrees C) and spontaneous dense granule release (> 0.01 nM of ATP at 20 degrees C vs. 0 nM of ATP at 37 degrees C), ADP and U46619 caused a significantly greater aggregation response and dense granule release at 20 degrees C, although there was no change in agonist sensitivity of platelets (effective dose of agonist necessary to induce 50% aggregation [ED50]: 1.00 +/− 0.35 microM ADP at 20 degrees C and 1.63 +/− 0.47 microM ADP at 37 degrees C; 8.26 +/− 3.65 pM U46619 at 20 degrees C and 18.97 +/− 4.82 pM U46619 at 37 degrees C). Platelets aggregated with arachidonic acid showed a significant decrease in aggregation and agonist sensitivity at 20 degrees C (ED50 118.7 +/− 44.4 microM) from those at 37 degrees C (ED50 25.6 +/− 7.2 microM), possibly as a result of the reduced enzymatic activity of cyclooxygenase and thromboxane synthase at the lower temperature. CONCLUSION: The data suggested that washed platelets chilled to 20 degrees C and aggregated are not more sensitive to agonists than are 37 degrees C controls, but rather that chilled platelets undergo greater spontaneous aggregation.