on April 7, 2008
Published online before print April 7, 2008, doi: 10.1161/HYPERTENSIONAHA.108.111070
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Submitted on January 28, 2008
From the Department of Medical Cell Biology (M.C., E.Y.L., Z.M., S.Z., U.J.E., A.P., A.E.G.P.), Division of Integrative Physiology, Uppsala University, Uppsala, Sweden; Institute of Vegetative Physiology (A.S., M.S., A.P.), University Hospital Charité, Humboldt University of Berlin, Germany; and the Division of Nephrology (Z.M.), Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China. * To whom correspondence should be addressed. E-mail: Mattias.Carlstrom{at}mcb.uu.se.
Abstract—Afferent arterioles were used to investigate the role of adenosine, angiotensin II, NO, and reactive oxygen species in the pathogenesis of increased tubuloglomerular feedback response in hydronephrosis. Hydronephrosis was induced in wild-type mice, superoxide dismutase-1 overexpressed mice (superoxide-dismutase-1 transgenic), and deficient mice (superoxide dismutase-1 knockout). Isotonic contractions in isolated perfused arterioles and mRNA expression of NO synthase isoforms, adenosine, and angiotensin II receptors were measured. In wild-type mice, NG-nitro-L-arginine methyl ester (L-NAME) did not change the basal arteriolar diameter of hydronephrotic kidneys (-6%) but reduced it in control (-12%) and contralateral arterioles (-43%). Angiotensin II mediated a weaker maximum contraction of hydronephrotic arterioles (-18%) than in control (-42%) and contralateral arterioles (-49%). The maximum adenosine-induced constriction was stronger in hydronephrotic (-19%) compared with control (-8%) and contralateral kidneys (±0%). The response to angiotensin II became stronger in the presence of adenosine in hydronephrotic kidneys and attenuated in contralateral arterioles. L-NAME increased angiotensin II responses of all of the groups but less in hydronephrotic kidneys. The mRNA expression of endothelial NO synthase and inducible NO synthase was upregulated in the hydronephrotic arterioles. No differences were found for adenosine or angiotensin II receptors. In superoxide dismutase-1 transgenic mice, strong but similar L-NAME response (-40%) was observed for all of the groups. This response was totally abolished in arterioles of hydronephrotic superoxide dismutase-1 knockout mice. In conclusion, hydronephrosis is associated with changes in the arteriolar reactivity of both hydronephrotic and contralateral kidneys. Increased oxidative stress, reduced NO availability, and stronger reactivity to adenosine of the hydronephrotic kidney may contribute to the enhanced tubuloglomerular feedback responsiveness in hydronephrosis and be involved in the development of hypertension.
Revised on February 13, 2008
Nitric Oxide Deficiency and Increased Adenosine Response of Afferent Arterioles in Hydronephrotic Mice With Hypertension
Mattias Carlström*;
Key words: angiotensin II • L-NAME • oxidative stress • NO synthase • superoxide dismutase • tubuloglomerular feedback