Glyoxylate lowers metabolic ATP in human platelets without altering adenylate energy charge or aggregation

Human blood platelets adhere to exposed collagen at the site of vascular injury, initiating a signaling cascade leading to fibrinogen activation, secretion of granules and aggregation, thus producing a stable thrombus. All these steps require metabolic ATP. In this study we have labeled the metabolic pool of ATP with nucleotides, treated platelets with various inhibitors and have monitored their ability to be activated. Incubating platelets with glyoxylate dramatically reduced the ATP level without a change in the adenylate energy charge (AEC). This reduction of ATP did not affect ADP-induced primary or secondary aggregation, whereas glyoxal, methyl glyoxal, or the combination of antimycin plus deoxyglucose reduced both ATP and AEC and inhibited aggregation. The reduction of ATP by glyoxylate was almost quantitatively matched by an increase in hypoxanthine without elevation of ADP. AMP, IMP or inosine, acetoacetate, aspartate, or glutamate had no effect on glyoxylate-induced breakdown of ATP, while pyruva...