| Abstrakt: |
The relative sensitivities for the various in vivo and in vitro tests for platelet activation are unknown. This was studied in a baboon model where limited and more substantial injury to the vascular endothelium was inflicted. The endothelium of a segment of the right carotid artery was removed with a balloon catheter on day 0 (limited de-endothelialisation), and that of the left carotid artery, abdominal aorta and left femoral artery on day 7 (substantial de-endothelialisation). Eight baboons (Papio ursinus) were used. Baseline tests for platelet activation (platelet volume, platelet density, platelet aggregate ratio, and platelet and plasma levels of platelet factor 4 [PF4] and beta-thromboglobulin [beta-TG]) were performed 7 days before de-endothelialisation and repeated on days 1, 9 and 16. The kinetics of indium-111-labelled platelets were measured after substantial de-endothelialisation. Sham operations were done on 3 animals exactly as in the test, except that the balloon injuries were not inflicted. No influence on the results of the platelet function tests was found. The only test capable of detecting limited injury to the endothelium was the measurement of plasma PF4. The mean platelet life-span (MPLS) shortened, mean platelet density decreased, the circulating platelet aggregate ratio decreased, and plasma levels of PF4 and beta-TG increased (P less than 0.05 in all instances) after the substantial endothelial injury. The mean platelet volume, intraplatelet PF4 and beta-TG, and the in vivo distribution and sites of sequestration of labelled platelets were poor tests for in vivo platelet activation.(ABSTRACT TRUNCATED AT 250 WORDS) |
