Platelet count and activation. Platelet count (A). Intensity of platelet aggregation (B) induced by 3 µmol/L ADP (open bar), 6 µmol/L ADP (grey bar) or 30 µg/ml collagen (filled bar). A significant decrease in platelet response to ADP or collagen was observed in the l-NAME group. Platelet aggregation induced by 6 µmol/L ADP (C) or 30 µg/ml collagen (D) was negatively correlated with systolic BP (r = −0.58, p = 0.006 and r = −0.75, p = 0.0007 respectively, all animals). Values are means ± SEM. *p < 0.05, **p < 0.005 versus controls. $p < 0.05 versus l-NAME.