Effects of the Nonapeptide SQ 20881 on Blood Pressure of Rats with Experimental Renovascular Hypertension

Abstract

Summary1. SQ 20881, the synthetic nonapeptide < Glu-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro, when infused iv at total dose levels of 3 to 25 mg/kg, lowered arterial blood pressure in normotensive rats and in three models of experimental renal hypertension, namely, "2-kidney" Goldblatt rats, aortaligated rats and "unclamped" renal pedicle-clamped rats, each anesthetized with urethane or pentobarbital. Such activity was questionable or not seen in "1 -kidney" Goldblatt rats or Grollman rats.2. SQ 20881 inhibited the pressor activity of exogenous angiotensin I, but not of angiotensin II, in normotensive rats and in "1-kidney" and "2-kidney" Goldblatt rats.3. The pattern of the responses elicited by the administration of SQ 20881 suggests that when the peptide decreased blood pressure, it acted, at least in part, by inhibiting the activity of angiotensin-converting enzyme.