Effect of angiotensin II on collagen-induced platelet activation in normotensive subjects

We examined the effect of angiotensin II (AII) on platelet activation in 15 normotensive volunteers. By measuring the initial phase of platelet aggregation on the optical density aggregation tracing and generation of thromboxane production, we demonstrated that AII enhances collagen-induced platelet activation. This enhancement in platelet activation is significantly greater when subjects are on a high salt than on a low salt diet. Furthermore, the increase in platelet activation parallels an increase in platelet AII receptor number. These parallel changes in platelet activation and platelet AII receptors provide a possible mechanism through which AII may affect platelet function.