Miasiro N, Oshiro ME, Paiva TB, Paiva AC. Role of the two N-terminal residues of angiotensin II in the production of tachyphylaxis.
Eur J Pharmacol 1983;
87:397-406. [PMID:
6852096 DOI:
10.1016/0014-2999(83)90078-x]
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Abstract
The structural requirements for the production of angiotensin tachyphylaxis in the guinea-pig ileum were studied by analyzing the tachyphylactic properties of the following synthetic analogues of angiotensin II (AII): [1-sarcosine]AII, [1-betaine]AII; [1-guanidinoacetic]AII; betainyl-AII; [2-lysine]AII; [2-ornithine]AII. In the non-atropinized ileum, no tachyphylaxis was observed with any of the following analogues: [2-lysine]AII, [2-ornithine]AII, [2-ornithine]AII, [1-betaine]AII and betainyl-AII. [1-Guanidinoacetic]AII induced tachyphylaxis, but to a smaller degree than AII, while [1-sarcosine]AII was significantly more tachyphylactic than AII. Similar results were obtained in the atropinized ileum, except that moderate tachyphylaxis was also observed with betainyl-AII and [1-betaine]AII. The analogues with lysine or ornithine residues in position 2 did not induce tachyphylaxis under any of the conditions studied. It is concluded that, besides the protonated N-terminal amino group, the guanidino group of the Arg2 side-chain is essential for the manifestation of angiotensin tachyphylaxis in the guinea-pig ileum.
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