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Hypoxic pulmonary vasoconstriction does not contribute to pulmonary blood flow heterogeneity in normoxia in normal supine humans

Hypoxic pulmonary vasoconstriction does not contribute to pulmonary blood flow heterogeneity in... Abstract We hypothesized that some of the heterogeneity of pulmonary blood flow present in the normal human lung in normoxia is due to hypoxic pulmonary vasoconstriction (HPV). If so, mild hyperoxia would decrease the heterogeneity of pulmonary perfusion, whereas it would be increased by mild hypoxia. To test this, six healthy nonsmoking subjects underwent magnetic resonance imaging (MRI) during 20 min of breathing different oxygen concentrations through a face mask normoxia, inspired O 2 fraction (F i O 2 ) = 0.21; hypoxia, F i O 2 = 0.125; hyperoxia, F i O 2 = 0.30 in balanced order. Data were acquired on a 1.5-T MRI scanner during a breath hold at functional residual capacity from both coronal and sagittal slices in the right lung. Arterial spin labeling was used to quantify the spatial distribution of pulmonary blood flow in milliliters per minute per cubic centimeter and fast low-angle shot to quantify the regional proton density, allowing perfusion to be expressed as density-normalized perfusion in milliliters per minute per gram. Neither mean proton density hypoxia, 0.46(0.18) g water/cm 3 ; normoxia, 0.47(0.18) g water/cm 3 ; hyperoxia, 0.48(0.17) g water/cm 3 ; P = 0.28 nor mean density-normalized perfusion hypoxia, 4.89(2.13) ml·min −1 ·g −1 ; normoxia, 4.94(1.88) ml·min −1 ·g −1 ; hyperoxia, 5.32(1.83) ml·min −1 ·g −1 ; P = 0.72 were significantly different between conditions in either imaging plane. Similarly, perfusion heterogeneity as measured by relative dispersion hypoxia, 0.74(0.16); normoxia, 0.74(0.10); hyperoxia, 0.76(0.18); P = 0.97, fractal dimension hypoxia, 1.21(0.04); normoxia, 1.19(0.03); hyperoxia, 1.20(0.04); P = 0.07, log normal shape parameter hypoxia, 0.62(0.11); normoxia, 0.72(0.11); hyperoxia, 0.70(0.13); P = 0.07, and geometric standard deviation hypoxia, 1.88(0.20); normoxia, 2.07(0.24); hyperoxia, 2.02(0.28); P = 0.11 was also not different. We conclude that HPV does not affect pulmonary perfusion heterogeneity in normoxia in the normal supine human lung. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Applied Physiology The American Physiological Society

Hypoxic pulmonary vasoconstriction does not contribute to pulmonary blood flow heterogeneity in normoxia in normal supine humans

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References (51)

Publisher
The American Physiological Society
Copyright
Copyright © 2011 the American Physiological Society
ISSN
8750-7587
eISSN
1522-1601
DOI
10.1152/japplphysiol.90759.2008
pmid
19057006
Publisher site
See Article on Publisher Site

Abstract

Abstract We hypothesized that some of the heterogeneity of pulmonary blood flow present in the normal human lung in normoxia is due to hypoxic pulmonary vasoconstriction (HPV). If so, mild hyperoxia would decrease the heterogeneity of pulmonary perfusion, whereas it would be increased by mild hypoxia. To test this, six healthy nonsmoking subjects underwent magnetic resonance imaging (MRI) during 20 min of breathing different oxygen concentrations through a face mask normoxia, inspired O 2 fraction (F i O 2 ) = 0.21; hypoxia, F i O 2 = 0.125; hyperoxia, F i O 2 = 0.30 in balanced order. Data were acquired on a 1.5-T MRI scanner during a breath hold at functional residual capacity from both coronal and sagittal slices in the right lung. Arterial spin labeling was used to quantify the spatial distribution of pulmonary blood flow in milliliters per minute per cubic centimeter and fast low-angle shot to quantify the regional proton density, allowing perfusion to be expressed as density-normalized perfusion in milliliters per minute per gram. Neither mean proton density hypoxia, 0.46(0.18) g water/cm 3 ; normoxia, 0.47(0.18) g water/cm 3 ; hyperoxia, 0.48(0.17) g water/cm 3 ; P = 0.28 nor mean density-normalized perfusion hypoxia, 4.89(2.13) ml·min −1 ·g −1 ; normoxia, 4.94(1.88) ml·min −1 ·g −1 ; hyperoxia, 5.32(1.83) ml·min −1 ·g −1 ; P = 0.72 were significantly different between conditions in either imaging plane. Similarly, perfusion heterogeneity as measured by relative dispersion hypoxia, 0.74(0.16); normoxia, 0.74(0.10); hyperoxia, 0.76(0.18); P = 0.97, fractal dimension hypoxia, 1.21(0.04); normoxia, 1.19(0.03); hyperoxia, 1.20(0.04); P = 0.07, log normal shape parameter hypoxia, 0.62(0.11); normoxia, 0.72(0.11); hyperoxia, 0.70(0.13); P = 0.07, and geometric standard deviation hypoxia, 1.88(0.20); normoxia, 2.07(0.24); hyperoxia, 2.02(0.28); P = 0.11 was also not different. We conclude that HPV does not affect pulmonary perfusion heterogeneity in normoxia in the normal supine human lung.

Journal

Journal of Applied Physiology – The American Physiological Society

Published: Apr 1, 2009

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