Ang(1-7) acts as a specific non-competitive antagonist of Ang II at type 1 angiotensin II receptors, inhibiting Ang II-induced pressor responses in vivo and depressing maximum response in vitro.
Effect estimate: apparent pA2 of 5.5
OBJECTIVE: The present study investigated the antagonism of the amino-terminal heptapeptide fragment of angiotensin II (des-Phe8-angiotensin II; Ang(1-7)) to angiotensin II (Ang II) both in vitro in rabbit aortae and in vivo in rats. METHODS AND RESULTS: In rabbit isolated endothelium intact aortic rings Ang(1-7) caused a concentration-related rightward displacement of the Ang II curve and depressed the maximum response to Ang II. By applying the data to a Schild plot an apparent pA2 of 5.5 was calculated. This depression of maximum response could be reversed by co-incubation of Ang(1-7) with the competitive angiotensin antagonist losartan. Ang(1-7) had no effect on the contractile responses of several other agonists. Intravenous infusion of 10 or 100 micrograms/kg per min Ang(1-7) had no effect on the resting blood pressure in the anaesthetized rat but inhibited Ang II-induced pressor responses. CONCLUSION: The present results show that Ang(1-7) is a specific non-competitive antagonist of Ang II at type 1 angiotensin II receptors.
Mahon et al. (Thu,) reported a other. Ang(1-7) vs. Ang II alone was evaluated on Antagonism to Ang II (contractile response in vitro, pressor response in vivo) (apparent pA2 of 5.5). Ang(1-7) acts as a specific non-competitive antagonist of Ang II at type 1 angiotensin II receptors, inhibiting Ang II-induced pressor responses in vivo and depressing maximum response in vitro.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: