Platelet adhesion and mural platelet thrombus formation on aortic subendothelium of rats, rabbits, and guinea pigs correlate negatively with the vascular PGI2 production.
This study investigates whether PGI2 produced locally by the vessel wall affects the interaction of platelets with subendothelium. Aortic endothelium was removed by a balloon catheter. Subsequent platelet deposition on subendothelium was assessed by morphometry. After 10 min exposure, surface coverage with adherent platelets in rats, rabbits, and guinea pigs amounted to 63% +/- 4, 82% +/- 3, and 97% +/- 1 (means +/- S.E.) (n greater than 5), and with microthrombi to 0 +/- 0, 6% +/- 2 and 15% +/- 4, respectively. Conversely, as measured by bioassay, excised aortic segments of rats, rabbits, and guinea pigs produced 135 +/- 14, 34 +/- 4, and less than 15 pmol of PGI2 per 10 mg of aorta per 30 min incubation in buffer, respectively (n = 4). In a second set of experiments, native blood from the aorta of a rabbit was circulated (30 ml/min) through a rat's de-endothelialized abdominal aorta and back into the vena cava of the rabbit. After a 5 min exposure at an approximate gamma w of 3000 sec-1, adhesion and aggregation of rabbit platelets on subendothelium of untreated rats amounted to 6% +/- 2 and 0 +/- 0, respectively. In contrast, on subendothelium of rats pretreated with 50 mg/kg ASA, which inhibits generation of PGI2 by greater than 80%, platelet adhesion and aggregation amounted to 55% +/- 11 and 19% +/- 7, respectively (n = 6, 2 alpha less than 0.01). The deposited thrombus volume per surface area differed by 3 orders of magnitude between the two groups. We conclude that platelet adhesion and aggregation on subendothelium correlate negatively with the generation of PGI2. Thus the smooth muscle cells of the media can produce sufficient amounts of PGI2 to locally influence the thrombogenicity of a de-endothelialized artery.
D000818:Animals; D001011:Aorta / Q000378:metabolism / Q000502:physiology*; D001241:Aspirin / Q000494:pharmacology; D001777:Blood Coagulation; D001792:Blood Platelets / Q000502:physiology*; D001808:Blood Vessels / Q000378:metabolism; D004727:Endothelium / Q000502:physiology; D011464:Epoprostenol / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000494:pharmacology; D006168:Guinea Pigs; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D010973:Platelet Adhesiveness; D010974:Platelet Aggregation; D011453:Prostaglandins / Q000096:biosynthesis*; D011817:Rabbits / Q000097:blood; D051381:Rats
D011453:Prostaglandins; D011464:Epoprostenol; D001241:Aspirin