Sar1Ile7]angiotensin III, a new selective antagonist of the pressor effect of angiotensin III in conscious rats |
| |
Authors: | R Tabrizchi G J Moore C C Pang |
| |
Institution: | Department of Pharmacology & Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver, Canada. |
| |
Abstract: | Two analogues of angiotensin III were compared as antagonists of the pressor response to angiotensin II (ANG II) and angiotensin III (ANG III) in conscious, unrestrained rats. Dose-mean arterial pressure (MAP) response curves were obtained for ANG II and ANG III in the absence or presence of Ile7]ANG III (1.3 x 10(-7) mol/kg) or Sar1 Ile7]ANG III (1.2 x 10(-7) mol/kg). In the presence of Ile7]ANG III, the dose-MAP response curves for ANG II and ANG III were significantly displaced to the right. Ile7]ANG III behaved as a partial agonist on ANG II but not ANG III receptors. In the presence of Sar1 Ile7]ANG III, the dose-MAP response curve for ANG III but not ANG II was significantly displaced to the right. This suggests that Sar1 Ile7]ANG III is a selective antagonist of ANG III in the vasculature. Ile7]ANG III, on the other hand, antagonizes both ANG II and ANG III receptors. Our results support the hypothesis of the existence of a sub-class of angiotensin receptors activated by ANG III in the vascular smooth muscle. |
| |
Keywords: | |
|
|