angiotensin I n.
A decapeptide that is the precursor to angiotensin II but is itself physiologically inactive.
angiotensin an·gi·o·ten·sin (ān'jē-ō-těn'sĭn)
Any of a group of peptides with vasoconstrictive activity that function physiologically in controlling arterial pressure.
Any of three polypeptide hormones that function in the body in controlling arterial pressure. The most important is known as angiotensin II, a powerful vasoconstrictor that stimulates steroid production by the adrenal glands, reduces fluid loss from the kidneys, and also functions as a neurotransmitter. Angiotensin II is formed from inactive angiotensin I by the action of angiotensin-converting enzyme (or ACE). See also ACE inhibitor, renin.