Istituto di Fisiologia Clinica     
Bertuglia S. The role of nitric oxide in capillary perfusion and oxygen delivery regulation during systemic hypoxia. In: Am J Physiol Heart Circ Physiol., vol. 288 (2) pp. H525 - H531. Am Phys Soc (ed.). Am Phys Society, 2005.
The role nitric oxide (NO) and oxygen radical species (ROS) in regulating capillary perfusion was studied in the hamster cheek pouch model during normoxia and after 20 min of exposure to 10% O2 and 90% N2. We measured PO2 by using phosphorescence quenching microscopy and ROS production in the systemic blood. Identical experiments were performed after treatment with the NO synthase inhibitor L-NMMA, and after the reinfusion of a NO-donor (DETA-NO) following treatment with L-NMMA. Hypoxia caused a significant decrease in the systemic PO2. During normoxia arteriolar intravascular PO2 decreased progressively from 47.0 ? 3.5 in the larger arterioles to 28.0 2.5 mm Hg in the terminal arterioles, conversely intravascular PO2 was 7 - 14 mm Hg and approximately uniform in all arterioles. Tissue PO2 was 85% of baseline. Hypoxia significantly dilated arterioles, reduced blood flow, increased capillary perfusion (15%) and ROS (72%) relative to baseline. Administration of L-NMMA during hypoxia further reduced capillary perfusion to 47% of baseline and increased ROS to 34% of baseline, both changes being significant. Tissue PO2 was reduced by 33% vs. the hypoxic group. Administration of DETA-NO after L-NMMA caused vasodilation, normalized ROS, and increased capillary perfusion and tissue PO2. These results indicate that during normoxia oxygen is supplied to the tissue mostly by the arterioles, while in hypoxia oxygen is supplied to tissue by capillaries by a NO concentration dependent mechanism that controls capillary perfusion and tissue PO2 involving capillary endothelial cell responses to the decrease in lipid peroxide formation controlled by NO availability during low PO2 conditions.
URL: http://ajpheart.physiology.org/cgi/reprint/288/2/H525?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&author1=bertuglia&searchid=1&FIRSTINDEX=0&sortspec=relevance&resourcetype=HWCIT
Subject ischemia reperfusion

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