Increased basal nitric oxide release despite enhanced free radical production in hypertension

Angelo Maffei, Roberta Poulet, Carmine Vecchione, Salvatore Colella, Luigi Fratta, Giacomo Frati, Valentina Trimarco, Bruno Trimarco, Giuseppe Lembo

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Introduction: Although in hypertension a defect in stimulated nitric oxide (NO) is well established, little is known about basal NO levels. Thus, we measured directly in vessels from normotensive [Wistar-Kyoto (WKY)] rats and spontaneously hypertensive rats (SHR) both basal and stimulated NO production using a novel technique [4,5-diaminofluorescein (DAF-2) fluorescence]. Methods: Isolated vessels were exposed to the fluorescent probe DAF-2. After the technique was validated with increasing doses of acetylcholine in the presence and absence of NG-nitro-L-arginine methyl ester (L-NAME), we measured NO production in vessels from WKY rats and SHR in the same experimental setting. Finally, to explore the impact of reactive oxygen species (RES) on NO release, we analysed the effect of an antioxidant, such as ascorbic acid, on basal and stimulated NO in aortic rings of WKY rats and SHR. Results: Aortic rings from SHR exhibited a higher basal NO production and a lower responsiveness to agonist-induced NO release as compared with those observed in WKY rats. Also in resistance vessels such as mesenteric arteries, basal NO production was higher in hypertension. In hypertensive rats, ascorbic acid was able to further increase basal NO release and recovered the impaired stimulated NO production, whereas no effect was detected in normotensive rats. Conclusions: Our data reveal an increased basal NO availability in hypertension despite the increased production of ROS, suggesting a greater complexity in hypertensive endothelial dysfunction when the analysis is focused on direct NO measurement.

Original languageEnglish
Pages (from-to)1135-1142
Number of pages8
JournalJournal of Hypertension
Volume20
Issue number6
DOIs
Publication statusPublished - Jun 2002

Fingerprint

Free Radicals
Nitric Oxide
Hypertension
Inbred WKY Rats
Inbred SHR Rats
NG-Nitroarginine Methyl Ester
Ascorbic Acid
Mesenteric Arteries
Fluorescent Dyes
Acetylcholine
Reactive Oxygen Species
Antioxidants
Fluorescence

Keywords

  • Arteries
  • DAF
  • Endothelium
  • Free radicals
  • Hypertension
  • Nitric oxide

ASJC Scopus subject areas

  • Endocrinology
  • Internal Medicine

Cite this

Increased basal nitric oxide release despite enhanced free radical production in hypertension. / Maffei, Angelo; Poulet, Roberta; Vecchione, Carmine; Colella, Salvatore; Fratta, Luigi; Frati, Giacomo; Trimarco, Valentina; Trimarco, Bruno; Lembo, Giuseppe.

In: Journal of Hypertension, Vol. 20, No. 6, 06.2002, p. 1135-1142.

Research output: Contribution to journalArticle

Maffei, Angelo ; Poulet, Roberta ; Vecchione, Carmine ; Colella, Salvatore ; Fratta, Luigi ; Frati, Giacomo ; Trimarco, Valentina ; Trimarco, Bruno ; Lembo, Giuseppe. / Increased basal nitric oxide release despite enhanced free radical production in hypertension. In: Journal of Hypertension. 2002 ; Vol. 20, No. 6. pp. 1135-1142.
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AU - Poulet, Roberta

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AU - Colella, Salvatore

AU - Fratta, Luigi

AU - Frati, Giacomo

AU - Trimarco, Valentina

AU - Trimarco, Bruno

AU - Lembo, Giuseppe

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N2 - Introduction: Although in hypertension a defect in stimulated nitric oxide (NO) is well established, little is known about basal NO levels. Thus, we measured directly in vessels from normotensive [Wistar-Kyoto (WKY)] rats and spontaneously hypertensive rats (SHR) both basal and stimulated NO production using a novel technique [4,5-diaminofluorescein (DAF-2) fluorescence]. Methods: Isolated vessels were exposed to the fluorescent probe DAF-2. After the technique was validated with increasing doses of acetylcholine in the presence and absence of NG-nitro-L-arginine methyl ester (L-NAME), we measured NO production in vessels from WKY rats and SHR in the same experimental setting. Finally, to explore the impact of reactive oxygen species (RES) on NO release, we analysed the effect of an antioxidant, such as ascorbic acid, on basal and stimulated NO in aortic rings of WKY rats and SHR. Results: Aortic rings from SHR exhibited a higher basal NO production and a lower responsiveness to agonist-induced NO release as compared with those observed in WKY rats. Also in resistance vessels such as mesenteric arteries, basal NO production was higher in hypertension. In hypertensive rats, ascorbic acid was able to further increase basal NO release and recovered the impaired stimulated NO production, whereas no effect was detected in normotensive rats. Conclusions: Our data reveal an increased basal NO availability in hypertension despite the increased production of ROS, suggesting a greater complexity in hypertensive endothelial dysfunction when the analysis is focused on direct NO measurement.

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