Sildenafil reduces L-NAME-induced severe hypertension and worsening of myocardial ischaemia-reperfusion damage in the rat

G. Rossoni, B. Manfredi, V. De Gennaro Colonna, M. Berti, M. Guazzi, F. Berti

Research output: Contribution to journalArticle

Abstract

Background and purpose: Phosphodiesterase-5 inhibitors are beneficial in pulmonary hypertension and congestive heart failure, the two conditions associated with coronary heart disease and ischaemia. We investigated whether sildenafil counteracts the cardiovascular alterations induced by N ω-nitro-L-arginine methyl ester (L-NAME) in the rat. Experimental approach: Sildenafil was given orally to rats at doses of 0.37, 0.75 or 1.5 mg kg -1day -1 for four weeks, either alone or with L-NAME (35-40 mg kg -1 day -1 in the drinking water). Systolic blood pressure and urinary parameters (6-keto-prostaglandin F , thromboxane B 2, 8-isoprostane-prostaglandin F and nitrite/nitrate) were measured in conscious rats. Isolated hearts were subjected to low flow ischaemia-reperfusion, and myocardial levels of guanosine 3′, 5′cyclic monophosphate (cGMP) were determined. Endothelial vascular dysfunction was examined in aortic rings. Key results: Sildenafil dose-dependently prevented the rise in systolic blood pressure in L-NAME-treated rats. This activity was associated with a normalization of urinary 8-isoprostane-prostaglandin F and other biochemical parameters. In perfused hearts, the post-ischaemic ventricular dysfunction was worse in preparations from L-NAME-treated rats than in controls. Sildenafil dose-dependently reduced this effect, and creatine kinase and lactate dehydrogenase release were lower too. cGMP levels, which were low in myocardial tissue from L-NAME-treated rats, were restored by sildenafil. In noradrenaline-precontracted aortic rings from L-NAME-treated rats acetylcholine lost its vasorelaxant effect, and sildenafil restored it. Conclusion and implications: In a rat model of chronic nitric oxide deprivation, where hypertension and aggravation of post-ischaemic ventricular dysfunction are associated with loss of vascular endothelium-relaxant function, sildenafil provided significant cardiovascular protection, primarily by maintaining tissue cGMP levels.

Original languageEnglish
Pages (from-to)567-576
Number of pages10
JournalBritish Journal of Pharmacology
Volume150
Issue number5
DOIs
Publication statusPublished - Mar 2007

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Keywords

  • L-NAME-induced hypertension
  • Myocardial ischaemia-reperfusion
  • Sildenafil

ASJC Scopus subject areas

  • Pharmacology

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