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This Article Full Text Full Text (PDF) All Versions of this Article: 294/4/H1914    most recent 01371.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Bertuglia, S. Search for Related Content PubMed PubMed Citation Articles by Bertuglia, S.

Intermittent hypoxia modulates nitric oxide-dependent vasodilation and capillary perfusion during ischemia-reperfusion-induced damage

Consiglio Nazionale delle Ricerche Institute of Clinical Physiology, University of Pisa, Pisa, Italy

Submitted 27 November 2007 ; accepted in final form 13 February 2008

The microvascular function of nitric oxide (NO) during ischemia-reperfusion (I/R) in intermittent hypoxia (IH)-pretreated hamsters was analyzed using 20 mg/kg of the nonselective NO inhibitor N-nitro-L-arginine methyl ester (L-NAME) and 5 mg/kg of the preferential inducible NO inhibitor S-methylisothiourea sulphate (SMT) injected before I/R. Studies were made in the hamster cheek pouch microcirculation (intravital fluorescence microscopy). IH consisted of 6 min of 8% O₂ breathing followed by 6 min of 21% O₂ for every 8 h for 21 days. Normoxia controls (NCs) were exposed to room air for the same period. The effects were characterized in terms of systemic hemodynamics, diameter, flow, wall shear stress in arterioles, capillary perfusion, and the concentrations of thiobarbituric acid-reactive substances (TBARS) and plasma NO, assessed as nitrite/nitrate (NOx) levels. IH did not change arterial blood pressure and increased hematocrit and shear stress. IH increased NOx and TBARS levels and reduced arterial diameter, blood flow, and capillary perfusion versus the NC. Conversely, TBARS and NOx were lower during I/R in IH-pretreated hamsters, resulting in vasodilation and the increase of capillary perfusion and shear stress. After IH, capillary perfusion was reduced by 24% (2.3%) and enhanced by 115% (1.7%) after I/R (P < 0.05). Both modalities of NO blockade decreased NOx generation and increased TBARS versus IH. L-NAME and SMT induced a significant decrease in arteriolar diameter, blood flow, and capillary perfusion (P < 0.05). L-NAME enhanced TBARS more than SMT and aggravated I/R damage. In conclusion, we demonstrated that preconditioning with IH greatly reduces oxidative stress and stimulates NO-induced vasodilation during I/R injury, thus maintaining capillary perfusion.

nitrite; nitrate; S-methylisothiourea; N-nitro-L-arginine methyl ester; shear stress; hematocrit