Impaired antiplatelet effects of aspirin associated with hypoxia and ATP release from erythrocytes. Studies in a system with flowing human blood.

Abstract

BACKGROUND:

We have explored how hypoxic conditions may affect the antiplatelet effects of aspirin.

MATERIALS AND METHODS:

For this purpose, a perfusion system containing a damaged vessel segment was modified in order to induce hypoxia (low Po2) in flowing blood. Blood samples were incubated with 50 mumol L-1 aspirin and divided into two aliquots, one being perfused under standard conditions (normoxic) and the other under hypoxic conditions. The interaction of platelets with the subendothelium was morphometrically evaluated.

RESULTS:

In studies with untreated blood under normoxic conditions, platelet interaction with the subendothelium was 0.3 +/- 0.1% of contact, 5.3 +/- 1.6% of adhesion, 24.3 +/- 3.3% of thrombus and 29.9 +/- 2.7% of total covered surface. Aspirin-treated blood perfused under normoxic conditions showed a marked decrease in thrombus with a concomitant increase in both platelet adhesion and covered surface percentages. However, when aspirin-treated blood was perfused under hypoxic conditions, platelet interaction was not significantly different from that observed in untreated blood. Hypoxia induced a 10-fold increase in ATP release from erythrocytes in the perfusates. If apyrase was added to the perfusates, ATP release was prevented and aspirin effects were evident again.

CONCLUSION:

Our results suggest that, under hypoxic conditions, the presence of aspirin would not help to inhibit further platelet activation.

• Authors: J Bozzo, M R Hernández, A M Galán, M Heras, A Ordinas, G Escolar
• Journal: European journal of clinical investigation (Eur J Clin Invest) Vol. 29 Issue 5 Pg. 438-44 (May 1999) ISSN: 0014-2972 [Print] England
• PMID: 10354201 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Platelet Aggregation Inhibitors
• Adenosine Triphosphate
• Aspirin

Topics

• Adenosine Triphosphate (metabolism)
• Animals
• Aorta (drug effects)
• Aspirin (pharmacology)
• Blood Gas Analysis
• Cell Hypoxia
• Erythrocyte Deformability (drug effects)
• Erythrocytes (drug effects, metabolism)
• Hemolysis (drug effects)
• Humans
• In Vitro Techniques
• Perfusion
• Platelet Aggregation (drug effects)
• Platelet Aggregation Inhibitors (pharmacology)
• Rabbits