In one aspect, this disclosure features compounds of formula (I) or a pharmaceutically acceptable salt thereof:AA1-Arg-Val-AA4-AA5-His-Pro-AA8-OH (I),in which AA1, AA4, AA5, and AA8 are defined in the specification. The compounds of formula (I) can be used to treat hypertension (e.g., hypertension induced by pregnancy), preeclampsia, or a renal disease induced by pregnancy.