Donate Help Contact The AHA Sign In Home
American Heart Association
Hypertension
Search: search_blue_button Advanced Search
Published Online
on May 19, 2008

Hypertension. 2008
Published online before print May 19, 2008, doi: 10.1161/HYPERTENSIONAHA.107.104158
A more recent version of this article appeared on July 1, 2008
This Article
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
52/1/150    most recent
HYPERTENSIONAHA.107.104158v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowRequest Permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Gauthier, K. M.
Right arrow Articles by Campbell, W. B.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Gauthier, K. M.
Right arrow Articles by Campbell, W. B.
Related Collections
Right arrow Biochemistry and metabolism
Right arrow ACE/Angiotension receptors
Right arrow Hypertension - basic studies
Right arrow Endothelium/vascular type/nitric oxide

Submitted on November 1, 2007
Revised on November 20, 2007

Angiotensin II Relaxations of Bovine Adrenal Cortical Arteries. Role of Angiotensin II Metabolites and Endothelial Nitric Oxide

Kathryn M. Gauthier*; David X. Zhang; Lijie Cui; Kasem Nithipatikom; and William B. Campbell

From the Department of Pharmacology and Toxicology (K.M.G., L.C., K.N., W.B.C.), and Internal Medicine and Cardiovascular Center (D.X.Z.), Medical College of Wisconsin, Milwaukee.

* To whom correspondence should be addressed. E-mail: kgauth{at}mcw.edu.

Abstract—Angiotensin (Ang) II regulates adrenal steroidogenesis and adrenal cortical arterial tone. Vascular metabolism could decrease Ang II concentrations and produce metabolites with vascular activity. Our goals were to study adrenal artery Ang II metabolism and to characterize metabolite vascular activity. Bovine adrenal cortical arteries were incubated with Ang II (100 nmol/L) for 10 and 30 minutes. Metabolites were analyzed by mass spectrometry. Ang (1-7), Ang III, and Ang IV concentrations were 146±21, 173±42 and 58±11 pg/mg at 10 minutes and 845±163, 70±14, and 31±3 pg/mg at 30 minutes, respectively. Concentration-related relaxations of U46619-preconstricted cortical arteries to Ang II (maximum relaxation=29±3%; EC50=3.4 pmol/L) were eliminated by endothelium removal and inhibited by the NO synthase inhibitor, nitro-L-arginine (30 µmol/L; maximum relaxation=14±7%). Ang II relaxations were enhanced by the angiotensin type-1 receptor antagonist losartan (1 µmol/L; maximum relaxation=41±3%; EC50=11 pmol/L). Losartan-enhanced Ang II relaxations were inhibited by nitro-L-arginine (maximum relaxation=18±5%) and the angiotensin type-2 receptor antagonist PD123319 (10 µmol/L; maximum relaxation=27±5%). Ang (1-7) and Ang III caused concentration-related relaxations with less potency (EC50=43 and 24 nmol/L, respectively) but similar efficacy (maximum relaxations=39±3% and 48±5%, respectively) as losartan-enhanced Ang II relaxations. Ang (1-7) relaxations were inhibited by nitro-L-arginine (maximum relaxation=16±4%) and the Ang (1-7) receptor antagonist 7D-Ala-Ang (1-7) (1 µmol/L; maximum relaxation=10±3%) and eliminated by endothelium removal. Thus, Ang II metabolism by adrenal cortical arteries to metabolites with decreased vascular activity represents an inactivation pathway possibly decreasing Ang II presentation to adrenal steroidogenic cells and limits Ang II vascular effects.


Key words: angiotensin (1-7) • angiotensin III • angiotensin IV • mass spectrometry