Aggregation of platelets from Tp-deficient mice is diminished in response to a high concentration of collagen in the presence of apyrase, A3P5P, and AR-C69931MX.

Platelets in plasma from Tp-deficient mice aggregated similarly to the wild-type platelets when activated with a high concentration (50 μg/mL) of collagen (A). ATP secretion and TxA2 production levels were undiminished from the Tp-deficient platelets in response to a high concentration of collagen (B). Tp-deficient and wild-type platelets were preincubated for 3 minutes with stirring in the presence of apyrase (10 U/mL), A3P5P (2 mM), and AR-C69931MX (2 μM) prior to stimulation with a high level of collagen. This treatment caused diminished aggregation of Tp-deficient platelets when compared to that of the wild-type platelets (C), but TxA2 production from Tp-deficient platelets was undiminished and similar to the wild-type platelets under the same conditions (D). Data were obtained from 6 tests. Bars represent means ± SEM. Aggregation of washed Tp-deficient platelets preincubated with the inhibitors (apyrase [10 U/mL], A3P5P [2 mM], and AR-C69931MX [2 μM]) and stimulated with 50 μg/mL collagen was inhibited by 10μg/mL hamster antimouse α_IIbβ₃ monoclonal antibody 1B5, but not by 10μg/mL hamster control IgG (E).