In vitro platelets/endothelial cells interactions in presence of acetylsalicylic acid at various dosages

Abstract

Venous endothelium is able to release in vitro substances which modifies platelet aggregation. A vascular fragment incubated in Michaelis buffer (pH 7.30), aliquoted and tested on platelet-rich-plasma partially inhibits the aggregometry parameters. Addition of acetylsalicylic acid (ASA) at ultra low dose (0.1 nM final solution in the incubation tube) presents a reversed effect on this inhibition. To explain this phenomenon, 6- keto-PGF 1α and von Willebrand factor were dosed in the incubation media. After determination of an active level of 6-keto-PGF 1α (200 pg/100μl), 2 series were made: series 1 included the values below 200 pg/100μl incubation media, series 2 , the values above 200 pg/100μl incubation media. When the vascular fragment was incubated as described above, the results of aggregometry ratio for series 1 were: test A (without ASA): 0.84±0.18, test B 1 (with 0.1 nM of ASA):0.87±0.13. For series 2 , they became: test A: 0.75±0.27, test B 1: 0.93±0.16. Control was always: 1.00± 0.00. For the same groups, 6-keto-PGF 1α values were: for series 1 , test A:81±57, test B 1:81±60 pg/100μl incubation medium, for series 2 , test A: 596±495, test B 1: 383±263 pg/100 μl incubation medium. Analyses were also performed with 2 high doses of ASA (B 2: 10 5 nM and B 3: 10 6 nM final solution) in the same experimental conditions. In these groups, aggregation parameters were decreased (0.86±0.14 for 10 5 nM, 0.84±0.15 for 10 6 nM) as well as 6-keto-PGF 1α production (189±199 for 10 5 nM, 152±182 for 10 6 nM). For these two last ASA treatments, comparison of the results in groups set up according to the sensitive 6-keto-PGF 1α value (200 pg/100μl solution) showed no modification. So it seems that a certain reactive state, specific of ultra low dose treatment is necessary for the vascular endothelium to be sensitive at such treatment.