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Gastroenterology. 2000 Jul;119(1):196-200.

Role of aortic nitric oxide synthase 3 (eNOS) in the systemic vasodilation of portal hypertension.

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  • 1Laboratoire d'Hémodynamique Splanchnique et de Biologie Vasculaire, INSERM Unité 481, Hôpital Beaujon, Clichy, France.

Abstract

BACKGROUND & AIMS:

In portal hypertension, the mechanisms responsible for nitric oxide (NO) overproduction and vasodilation have not yet been clearly identified. One hypothesis is that NO synthase (NOS) 3 is overactivated because of shear stress in endothelial cells caused by hyperkinetic circulation. The aim of this study was to evaluate aortic NOS3 after a reduction of blood flow by long-time beta-adrenoceptor antagonist administration.

METHODS:

Propranolol or atenolol was administered by gavage in portal vein-stenosed and sham-operated rats. The vascular reactivity of thoracic aortic rings to phenylephrine, total aortic NOS activity, and aortic NOS3 messenger RNA and protein expressions were studied.

RESULTS:

After propranolol or atenolol administration, the aortic hyporesponse returned to normal in portal vein-stenosed rats. Total aortic NOS activity was higher in portal vein-stenosed aortas and significantly decreased after beta-blocker administration. Aortic NOS3 expressions were more marked in portal vein-stenosed aortas than in controls, but NOS3 expressions were reduced after propranolol administration.

CONCLUSIONS:

In portal hypertension, aortic NOS3 activity and expressions are enhanced but return to normal after beta-blocker administration. These results suggest that in portal hypertension, increased shear stress, related to high blood flow, induces enhanced aortic NOS3.

PMID:
10889169
[PubMed - indexed for MEDLINE]
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