Chronic hypoxia-induced pulmonary hypertension does/does not lead to loss of pulmonary vasculature

Abstract

POINT-COUNTERPOINT COMMENTSChronic hypoxia-induced pulmonary hypertension does/does not lead to loss of pulmonary vasculatureJohn T. BergJohn T. BergPublished Online:01 Oct 2007https://doi.org/10.1152/japplphysiol.00739.2007MoreSectionsPDF (27 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat The following letter is in response to Point:Counterpoint: “Chronic hypoxia-induced pulmonary hypertension does/does not lead to loss of pulmonary vasculature” that appears in this issue.To the Editor: In their initial statement supporting the hypothesized loss of precapillary arteries in chronic hypoxia Rabinovitch, Chesler, and Molthen (6) provide evidence derived from perfusion studies using contrast dyes and other markers. In reply, McLoughlin and McMurtry (5) introduce the problem of artifactual measurements resulting from hypoxic pulmonary vasoconstriction (HPV) of pulmonary arteries. I believe that clarification of how HPV may cause the proposed loss of vessels to occur may contribute to the debate. One way this could happen is through uneven HPV where flow in some vascular channels may become entirely blocked and downstream vessels would appear to be lost through a lack of perfusion. Hultgren (4) initially introduced the concept of uneven HPV in pulmonary arteries to explain the observed patchy distribution of high-altitude pulmonary edema in humans. Anatomically, pulmonary arteries in the adult human lung have a highly variable distribution of smooth muscle (2) consistent with the observed variability of HPV response between individuals. Studies by Dawson et al. (1), using the double-indicator dilution method, showed that hypoxia causes more than a doubling of transit times for infused indicator agents in dog lungs, suggesting that flow rates through parallel channels become more variable with hypoxia. More recently, Hopkins et al. (3), using functional magnetic resonance imaging techniques, provide additional evidence for uneven HPV. It is therefore likely that at least some of the data presented in defense of vessel loss as a cause of pulmonary hypertension may be the result of uneven HPV and artifactual inclusion of HPV-blocked vessels.REFERENCES1 Dawson CA, Bronikowski TA, Linehan JH, Hakim TS. Influence of pulmonary vasoconstriction on lung water and perfusion heterogeneity. J Appl Physiol 54: 654–660, 1983.Link | ISI | Google Scholar2 deMello D, Reid LM. Arteries and veins. In: The Lung: Scientific Foundations, edited by Crystal RG and West JB. New York: Raven, 1991, p. 767–777.Google Scholar3 Hopkins SR, Garg J, Bolar DS, Balouch J, Levin DL. Pulmonary blood flow heterogeneity during hypoxia and high-altitude pulmonary edema. Am J Respir Crit Care Med 171: 83–87, 2005.Crossref | PubMed | ISI | Google Scholar4 Hultgren HN. High altitude pulmonary edema. In: Biomedicine of High Terrestrial Altitude, edited by Hegnauer AH. New York: Springer-Verlag, 1969, p. 131–141.Google Scholar5 McLoughlin P, McMurtry I. Counterpoint: Chronic hypoxia-induced pulmonary hypertension does not lead to loss of pulmonary vasculature. J Appl Physiol; doi:10.1152/japplphysiol.00274a.2007.Google Scholar6 Rabinovitch M, Chesler N, Molthen RC. Point: Chronic hypoxia-induced pulmonary hypertension does lead to loss of pulmonary vasculature. J Appl Physiol; doi:10.1152/japplphysiol.00274.2007.Google Scholar Download PDF Previous Back to Top Next FiguresReferencesRelatedInformationCited ByCellular Pathways Promoting Pulmonary Vascular Remodeling by HypoxiaLarissa A. Shimoda3 June 2020 | Physiology, Vol. 35, No. 4Lung Circulation15 March 2016Vascular remodeling in pulmonary hypertension19 January 2013 | Journal of Molecular Medicine, Vol. 91, No. 3Chronic hypoxia-induced pulmonary hypertension in rat: the best animal model for studying pulmonary vasoconstriction and vascular medial hypertrophyDrug Discovery Today: Disease Models, Vol. 7, No. 3-4 More from this issue > Volume 103Issue 4October 2007Pages 1455-1455 Copyright & PermissionsCopyright © 2007 the American Physiological Societyhttps://doi.org/10.1152/japplphysiol.00739.2007PubMed17916681History Published online 1 October 2007 Published in print 1 October 2007 Metrics