The potent platelet inhibitory effects of S-nitrosated albumin coating of artificial surfaces

OBJECTIVES We studied the antithrombotic effect of coating glass, collagen and metal stent surfaces with bovine serum albumin (BSA) covalently modified to carry S-NO functional groups denoted (pS-NO-BSA). METHODS Video-enhanced light microscopy was used to visualize canine blood platelet adhesion and aggregation in parallel plate glass chamber. Platelet adhesion was observed for 60 min on glass, glass coated with BSA, glass coated with pS-NO-BSA, collagen I (CO) surface, CO coated with BS and CO coated with pS-NO-BSA. We also coated Palmaz-Shatz (P-S) stents with pS-NO-BSA. Coated and uncoated stents were then immersed in porcine platelet-rich plasm for two min and the platelet cyclic GMP level was measured. In six anesthetized pigs, coated and uncoated stents were placed in the carotid arteries and [111In]-labeled platelets were circulated for 2 h. The stented arteries were then removed and placed in gamm well counter. RESULTS There was significantly less platelet attachment, adhesion and aggregation on the pS-NO-BS coated surfaces compared with the BS coated and uncoated surfaces. The pS-NO-BS coating increased the platelet cGMP levels to 5.9 ± 0.7 pmoles/108 platelets compared with 2.7 ± 0.9 pmoles/108 platelets for control (p < 0.01). The average gamm ray count from [111In]-labeled platelets that attached to the coated stents was 90,000 ± 42,000/min and 435,000 ± 290,000/min for the uncoated stents (p < 0.01). CONCLUSIONS The pS-NO-BS coating of thrombogenic surfaces reduces platelet adhesion and aggregation, possibly by increasing the platelet cGMP. This inhibitory effect appears to be consequence of the direct antiplatelet actions of NO combined with the antiadhesive properties of albumin.