PT  - JOURNAL ARTICLE
AU  - A Husain
AU  - S F Pajka
AU  - S M Taylor
AU  - R C Speth
TI  - Monoiodinated angiotensin II is a potent, full agonist analog of angiotensin II.
DP  - 1986 Oct 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 71--77
VI  - 239
IP  - 1
4099  - http://jpet.aspetjournals.org/content/239/1/71.short
4100  - http://jpet.aspetjournals.org/content/239/1/71.full
SO  - J Pharmacol Exp Ther1986 Oct 01; 239
AB  - Mono 125I-angiotensin II (Ang II) has been used extensively as a radioligand to identify Ang II receptors whereas its receptor binding properties are well characterized, its biological activity has been less well studied. To examine this issue, nonradioisotopic monoiodo-Ang II was prepared and compared to Ang II. Monoiodo-Ang II was found to be a potent, full agonist in in vivo bioassays and a more potent (2.5-fold) pressor agent than the native hormone Ang II in the pithed rat. In eliciting dipsogenic responses monoiodo-Ang II was equipotent to Ang II, but was less potent (2.7-fold) than Ang II in contracting rat aortic strips. These results suggest that the well characterized binding affinity of monoiodo-Ang II is representative of its biological activity (40-250% of the activity of Ang II). The variation in relative peptide potency is consistent with the hypothesis of a heterogeneity of Ang II receptors. Most importantly, the similar efficacies between Ang II and monoiodo-Ang II indicate that the monoiodinated Ang II is a suitable ligand for the study of Ang II receptors.