[Sar1, Ile8]-Angiotensin II is a peptide that has multiple effects on vascular smooth muscle, including contraction of normal arteries and hypertrophy or hyperplasia of cultured cells or diseased vessels. In Vitro: Angiotensin II has multiple effects on vascular smooth muscle, including contraction of normal arteries and hypertrophy or hyperplasia of cultured cells or diseased vessels. Angiotensin II activates both the NADPH and NADH oxidases, and stimulates superoxide anion formation in vascular smooth muscle cells^[1].