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. Author manuscript; available in PMC: 2009 Aug 17.
Published in final edited form as: J Biol Chem. 1999 Dec 17;274(51):36321–36327. doi: 10.1074/jbc.274.51.36321

FIG. 4. Aggregation of thrombin-stimulated platelets is calpaindependent.

FIG. 4

Calpastat (50 µm) but not calpastat-Ala (50 µm) inhibits thrombin-induced (1.0 unit/ml) platelet aggregation. Aggregation of stirred platelets was initiated by thrombin treatment, as described (see “Experimental Procedures”). The abscissa, indicating time, is marked by broken lines in intervals of 15 s. The ordinate, indicating percentage of light transmission, is marked by broken lines in intervals of 10%. 100% and 0% light transmission were defined by buffer and unaggregated platelets in buffer, respectively. The time of thrombin addition is indicated with an arrow. Gel-filtered platelets were preincubated with calpastat or calpastat-Ala for 20 min before recalcification and subsequent addition of thrombin.