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Effects of anticoagulant on pH, ionized calcium concentration, and agonist-induced platelet aggregation in canine platelet-rich plasma

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  • 1 Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104.
  • | 2 Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104.
  • | 3 Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 18453.

Abstract

Objective—To compare effects of 3.8% sodium citrate and anticoagulant citrate dextrose solution National Institutes of Health formula A (ACD-A) on pH, extracellular ionized calcium (iCa) concentration, and platelet aggregation in canine platelet-rich plasma (PRP).

Sample Population—Samples from 12 dogs.

Procedures—Blood samples were collected into 3.8% sodium citrate (dilution, 1:9) and ACD-A (dilution, 1:5). Platelet function, pH, and iCa concentration were evaluated in PRP. Platelet agonists were ADP, γ-thrombin, and convulxin; final concentrations of each were 20μm, 100nM, and 20nM, respectively. Washed platelets were used to evaluate effects of varying the pH and iCa concentration.

Results—Mean pH and iCa concentration were significantly greater in 3.8% sodium citrate PRP than ACD-A PRP. Platelet aggregation induced by ADP and γ-thrombin was markedly diminished in ACD-A PRP, compared with results for 3.8% sodium citrate PRP. Anticoagulant had no effect on amplitude of convulxin-induced platelet aggregation. In washed platelet suspensions (pH, 7.4), there were no differences in amplitude of platelet aggregation induced by convulxin or γ-thrombin at various iCa concentrations. Varying the pH had no effect on amplitude of aggregation induced by convulxin or γ-thrombin, but the aggregation rate increased with increasing pH for both agonists.

Conclusions and Clinical Relevance—Aggregation of canine platelets induced by ADP and γ-thrombin was negligible in ACD-A PRP, which suggested an increase in extraplatelet hydrogen ion concentration inhibits signaling triggered by these agonists but not by convulxin. Choice of anticoagulant may influence results of in vitro evaluation of platelet function, which can lead to erroneous conclusions.

Contributor Notes

Supported by a clinical research fund from the Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, and by a grant from the National Institutes of Health (No. RR02512).

The authors gratefully acknowledge Dr. Mark Haskins for providing dogs for the study and Patricia A. O'Donnell and Caroline Bryan for technical assistance.

Address correspondence to Dr. Callan.