any of several vasoconstrictor substances (trade name Hypertensin) that cause narrowing of blood vessels
"The doctor explained that the new medication works by blocking angiotensin to prevent those dangerous vasoconstrictor substances from narrowing the patient's blood vessels."
Any of several polypeptides that narrow blood vessels and thus regulate arterial pressure.
"High levels of angiotensin in his bloodstream caused his blood vessels to constrict, leading to a dangerous spike in his blood pressure."