Upregulation of antithrombotic ectonucleotidases by aspirin in human endothelial cells in-vitro.

Ecto ATP-diphosphohydrolase (apyrase) activity of human endothelial cells following aspirin treatment has been studied in-vitro. It was shown by HPLC analysis of supernatant samples that pre-incubation of the cultures with aspirin resulted in a significantly increased turnover of supplemented ATP into its degradation products (ADP and AMP). Enhanced expression of ectoenzyme after aspirin treatment could be observed as demonstrated by immunofluorescence-staining with monoclonal anti-apyrase antibodies. This suggests enhancement of endothelial ATP-diphosphohydrolase activity induced by aspirin. The present data obtained in human vascular cells in-vitro are in line with results from previous animal studies in-vivo, suggesting a novel cyclooxygenase-independent antithrombotic activity of aspirin.