AngiotensinII is a potent direct vasoconstrictor, causing arteries and veins to constrict, so leading to an increase in blood pressure. Angiotensin also potentiates the release of norepinephrine by a direct action on postganglionic sympathetic fibers.
4-hydroxy Valsartan is a major metabolite of the angiotensinII type 1 (AT1) receptor antagonist valsartan . It reduces platelet aggregation induced by epinephrine and collagen but not ADP in human whole blood.