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Pulmonary vascular innervation and its role in responses to hypoxia: size matters!
MedLine Citation:
PMID:  22052922     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
The pulmonary vasculature is innervated by specific subsets of sympathetic, parasympathetic, and sensory nerve fibers. In contrast to most other organs, innervation density is highest at large-caliber vessels and decreases toward the periphery, and reactivity to vasoactive compounds also changes along the course. In some species, such as the experimentally widely used rodents rat and mouse, autonomic efferent (sympathetic and parasympathetic) perivascular axons barely reach beyond the lung hilus, whereas in humans this innervation extends to small intrapulmonary vessels. Throughout, the most distal arterioles (i.e., intraacinar arteries equipped with an incomplete coat of intermediate cells instead of a full muscular wall) are devoid of innervation. Altogether, 10 vasoactive substances (3 small molecular transmitters and 7 neuropeptides) at minimum have been identified in various combinations (cotransmission) in pulmonary vascular axons. Analysis of this "neurochemical coding" has been provided only for the guinea pig so far, but not for humans or for animal species commonly used for pulmonary vascular research. Sympathetic pulmonary vascular neurons are reflexively activated via arterial chemoreceptors when arterial Po(2) is lowered and adapt the pulmonary vasculature to this condition of increased pulmonary blood flow by α(1)-adrenoreceptor-mediated increase in vascular impedance primarily at large vessels. In contrast, neither they nor other nerve fibers play a role in the local hypoxic vasoconstriction triggered by low alveolar Po(2), which serves to match perfusion to ventilation. The major potential role of the pulmonary vascular innervation, autonomic and sensory, lies in the pronounced trophic activities of its transmitters.
Authors:
Wolfgang Kummer
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Proceedings of the American Thoracic Society     Volume:  8     ISSN:  1943-5665     ISO Abbreviation:  Proc Am Thorac Soc     Publication Date:  2011 Nov 
Date Detail:
Created Date:  2011-11-04     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101203596     Medline TA:  Proc Am Thorac Soc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  471-6     Citation Subset:  IM    
Affiliation:
Institute for Anatomy and Cell Biology, Justus-Liebig-University Giessen, Aulweg 123, D-35385 Giessen, Germany. wolfgang.kummer@anatomie.med.uni-giessen.de.
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