Influence of caffeine on the responsiveness of human platelet to agonists

Choi, Jong Weon

doi:10.1016/s0049-3848(03)00348-7

Cited by 25 publications

(34 citation statements)

References 7 publications

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“…Interestingly, the 4°C‐stored PLTs showed a heightened aggregatory response to shear stress compared to fresh PLTs. Previous studies have shown that PLTs stored at 4°C long term (24‐48 hr), compared to fresh PLTs, show a muted aggregation response to chemical agonists including thrombin, ADP, collagen, and epinephrine and reduced sensitivity to signal transduction‐inhibiting agents . In light of these reports, results suggest that shear stress, a mechanical agonist, may act differently than chemical agonists in aggregating stored PLTs.…”

Section: Discussionmentioning

confidence: 91%

Enhanced shear‐induced platelet aggregation due to low‐temperature storage

et al. 2012

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BACKGROUND Refrigeration of platelets (PLTs) offers an attractive alternative to the currently practiced storage at room temperature since it may mitigate problems associated with bacterial contamination and extend storage lifetime. Refrigeration causes a number of biophysical and biochemical changes in PLTs and decreases PLT circulation time in vivo. However, the effect of refrigeration on PLT hemostatic functions under physiologic and pathophysiologic shear conditions has not been adequately characterized. STUDY DESIGN AND METHODS Washed PLTs prepared from either fresh PLT-rich plasma (PRP) or PRP stored at 4°C for 2 days was mixed with exogenous von Willebrand factor (VWF) and fibrinogen and sheared in a cone-and-plate viscometer. PLT aggregation, activation, and VWF binding after shear and glycoprotein (GP) Ibα receptor expression and ristocetin-induced PLT agglutination were measured. RESULTS PLTs stored at 4°C for 2 days aggregated significantly more than fresh PLTs particularly at high shear rates (10,000/sec), and this increase was independent of PLT concentration or suspension viscosity. Further, refrigerated PLTs showed a greater increase in GP Ibα–dependent PLT activation under shear and also bound more VWF than fresh PLTs. However, the GP Ibα expression levels as measured by three different antibodies were significantly lower in refrigerated PLTs than in fresh PLTs, and refrigeration resulted in a modest decrease in ristocetin-induced PLT agglutination. CONCLUSION The combined results demonstrate that refrigeration increases PLT aggregation under high shear, but not static, conditions and also increases shear-induced VWF binding and PLT activation. Clinically, enhanced shear-induced PLT aggregation due to low temperature storage may be a beneficial strategy to prevent severe bleeding in trauma.

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Section: Discussionmentioning

confidence: 91%

Enhanced shear‐induced platelet aggregation due to low‐temperature storage

et al. 2012

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“…Equine platelet function was also examined in relation to glucocorticoid hormones; these studies showed that although glucocorticoids can increase the number of circulating platelets, neutrophils, and red blood cells, platelet aggregation is inhibited [7]. Other researchers limited themselves to studying pharmacokinetics and bioavailability of drugs, such theophilline and aminophylline, in horses [10,14] while the effects of some xanthine derivates on some hemostasis indices were only evaluated in humans [8,19]. In horses, the action of aminophylline on ADP-induced platelet aggregation has not been studied.…”

Section: Introductionmentioning

confidence: 99%

Effects of hydrocortisone and aminophylline on the aggregation of equine plateletsin vitro

et al. 2011

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The purpose of this study was to evaluate in vitro the effects of hydrocortisone and aminophylline on adenosine diphosphate (ADP)-induced platelet aggregation in horses. Blood samples from 30 healthy Thoroughbred horses were collected by via jugular venipuncture to assess platelet aggregation. Platelet-rich and platelet-poor plasma were prepared from all samples by centrifugation and divided into three different aliquots. In the first aliquot, platelet aggregation was measured after platelet activation with 1 µM and 0.5 µM ADP (Group A). In the other two aliquots, the effect of a 10 min preincubation with hydrocortisone (Group B) or aminophylline (Group C) on ADP-induced aggregation at final ADP concentrations of 1 µM and 0.5 µM was observed. Platelet aggregation, recorded by an aggregometer, was evaluated by measuring the maximum degree of platelet aggregation and the initial velocities of platelet aggregation were obtained. Our results demonstrated the inhibitory effect of hydrocortisone and the induction effect of aminophylline on equine platelet responses in vitro.

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“…48 Furthermore, cold storage better preserves the platelets' capacity to aggregate and secrete their granule contents upon later stimulation at 37°C. 49,50 AA depletion will reduce platelet activation during preparation of platelet concentrates, since mechanical disturbances can activate this metabolic pathway. 51 Since this process is reversible, addition of AA prior to transfusion -or when transfused platelets bind plasma AA-albumin in the circulation -will fully restore hemostatic functions.…”

Section: Discussionmentioning

confidence: 99%