Journal Article

Different Natriuretic Responses in Obese and Lean Rats in Response to Nitric Oxide Reduction

Marta A. Ambrozewicz, Ali A. Khraibi, Fatma Simsek-Duran, Sophia C. DeBose, Hind A. Baydoun and Anca D. Dobrian

in American Journal of Hypertension

Published on behalf of American Journal of Hypertension, Ltd.

Volume 24, issue 8, pages 943-950
Published in print August 2011 | ISSN: 0895-7061
Published online August 2011 | e-ISSN: 1941-7225 | DOI: https://dx.doi.org/10.1038/ajh.2011.79
Different Natriuretic Responses in Obese and Lean Rats in Response to Nitric Oxide Reduction

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Background

Nitric oxide (NO) is an important regulator of renal sodium transport and participates in the control of natriuresis and diuresis. In obesity, the nitric oxide bioavailability was reportedly reduced, which may contribute to the maintenance of hypertension. The aim of this study was to determine the effect of NO depletion on renal sodium handling in a model of diet-induced obesity hypertension.

Methods

Obese hypertensive (obesity-prone (OP)) and lean normotensive (obesity-resistant (OR)) Sprague–Dawley rats were treated with 1.2mg/kg/day NG-nitro-L-arginine-methyl ester (L-NAME) for 4 weeks to inhibit NO synthesis. Acute pressure natriuresis and diuresis were measured in response to an increase in perfusion pressure. NHE3 and Na+, K+-ATPase protein expression were measured by Western blot and NHE3 activity was determined as the rate of pH change in brush border membrane vesicles. NHE3 membrane localization was determined by confocal microscopy.

Results

L-NAME did not significantly attenuate the natriuretic and diuretic responses to increases in renal perfusion pressure (RPP) in OP rats while inducing a significant reduction in OR rats. Following chronic NO inhibition, NHE3 protein expression and activity and Na+, K+-ATPase protein expression were significantly increased in the OR but not in the OP group. Immunofluorescence studies indicated that the increase in NHE3 activity could be, at least in part, due to NHE3 membrane trafficking.

Conclusions

Obese hypertensive rats have a weaker natriuretic response in response to NO inhibition compared to lean rats and the mechanism involves different regulation of the apical sodium exchanger NHE3 expression, activity, and trafficking.

American Journal of Hypertension, advance online publication 12 May 2011; doi:10.1038/ajh.2011.79

Keywords: blood pressure; diet-induced obesity; hypertension; pressure natriuresis; sodium transporters

Journal Article.  5008 words.  Illustrated.

Subjects: Bariatric Surgery ; Endocrinology and Diabetes

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