Saralasin

Saralasin is a competitive angiotensin II receptor antagonist with partial agonistic activity. The aminopeptide sequence for saralasin differs from angiotensin II at three sites:
 * At position 1, sarcosine replaces aspartic acid, thereby increasing the affinity for vascular smooth muscle AT II receptors and making sara resistant to degradation by aminopeptidases.
 * At position 5, isoleucine is replaced by valine
 * At position 8, phenylalanine is replaced by alanine which leads to a smaller stimulatory effect. Saralasin was used to distinguish renovascular hypertension from essential hypertension before its discontinuation in January 1984 because of many false-positive and false-negative reports.