Agonist-induced cGMP production is diminished and collagen-induced platelet secretion and aggregation are attenuated in sGC β₁ deficient platelets. (A) Washed platelets from wild-type (sGC^+/+) or sGC β₁ deficient mice (sGC^−/−) resuspended in Tyrode's solution were stimulated with selected concentrations of either thrombin or collagen at 37°C for 5 minutes and solubilized by adding ice-cold 12% (wt/vol) trichloroacetic acid. cGMP concentrations were determined using a cGMP enzyme immunoassay kit. Results are expressed as mean ± SD (n = 3). Means and SD of triplicates are shown from 1 representative experiment of 3. (B) Washed platelets from wild-type (sGC^+/+) or sGC β₁ deficient mice (sGC^–/–) were stimulated with various concentrations of collagen in a lumi-aggregometer at 37°C. Real-time ATP secretion and platelet aggregation were recorded simultaneously. Data shown are representative of 4 independent experiments.