[Sar1, Ile8]-Angiotensin II (TFA) is a peptide with 8 amino acids in the series, including an unnatural amino acid Sar. [Sar1, Ile8]-Angiotensin II (TFA) mainly plays a variety of roles in vascular smooth muscle cells. Its main physiological functions include the contraction of normal arteries, the hypertrophy or proliferation of cultured cells or diseased blood vessels.