Increased platelet aggregation due to chilling to 20 degrees C is not related to increased sensitivity to agonists.

Abstract

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.

• Authors: T N Hansen, K G Brockbank
• Journal: Transfusion (Transfusion) Vol. 37 Issue 7 Pg. 696-702 (Jul 1997) ISSN: 0041-1132 [Print] United States
• PMID: 9225932 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Prostaglandin Endoperoxides, Synthetic
• Vasoconstrictor Agents
• Arachidonic Acid
• Thromboxane B2
• Thromboxane A2
• Adenosine Diphosphate
• 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid

Topics

• 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid
• Adenosine Diphosphate (pharmacology)
• Analysis of Variance
• Arachidonic Acid (pharmacology)
• Blood Platelets (chemistry)
• Cold Temperature
• Humans
• Platelet Aggregation (drug effects, physiology)
• Prostaglandin Endoperoxides, Synthetic (pharmacology)
• Thromboxane A2 (analogs & derivatives, pharmacology)
• Thromboxane B2 (blood)
• Vasoconstrictor Agents (pharmacology)