The role of metabolic energy in platelet-collagen adhesion

The adhesion of rabbit gel filtered platelets (GFP) to collagen-Sepharose includes both energy dependent and independent phases. The energy dependent phase was evident by the partial reduction of platelet adhesion to immobilized collagen in the presence of metabolic inhibitors. Antimycin-A (AA) plus 2-deoxy-D-glucose (2DG) decreased but did not completely inhibit adhesion and subsequent release, the effects on the latter being additive. The combination of AA, 2DG, and glucono-δ-lactone did not reduce adhesion more than 45 percent. The inhibitory effects of AA in glucose-free buffer were time and dose related, and the addition of 0.1 percent glucose abolished these effects. Platelets treated with AA plus 2DG (a) adhered to collagen with suppressed release response, (b) exhibited contact adhesion to collagen fibrils detectable by scanning electron microscopy (SEM), and (c) implicated a possible equilibrium state of adhesion to immobilized collagen. It is concluded that during the adhesion process there exists an initial energy independent contact phase followed by an irreversible energy dependent phase.