Document Detail


Sympathetic drive to liver and nonhepatic splanchnic tissue during heavy exercise.
MedLine Citation:
PMID:  9104862     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The contribution of sympathetic drive and vascular catecholamine delivery to the splanchnic bed during heavy exercise was studied in dogs that underwent a laparotomy during which flow probes were implanted onto the portal vein and hepatic artery and catheters were inserted into the carotid artery, portal vein, and hepatic vein. At least 16 days after surgery, dogs completed a 20-min heavy exercise protocol (mean work rate of 5.7 +/- 1 miles/h, 20 +/- 2% grade). Arterial epinephrine (Epi) and norepinephrine (NE) increased by approximately 500 and approximately 900 pg/ml, respectively, after 20 min of heavy exercise. Because Epi is not released from the splanchnic bed and because Epi fractional extraction (FX) = NE FX, NE uptake by splanchnic tissue can be calculated despite simultaneous release of NE. Basal nonhepatic splanchnic (NHS) FX increased from a basal rate of 0.52 +/- 0.09 to a peak of 0.64 +/- 0.05 at 10 min of exercise. Hepatic Epi FX increased from a basal rate of 0.68 +/- 0.10 to 0.81 +/- 0.09 at 20 min of exercise. Even though NHS extraction of Epi reduced portal vein Epi levels by approximately 60%, the release of NE from NHS tissue maintained portal vein NE at levels similar to those in arterial blood. NHS NE spillover increased from a basal rate of 5.7 +/- 1.4 to 11.7 +/- 2.8 ng x kg(-1) x min(-1) at 20 min of exercise. Hepatic NE spillover increased from a basal rate of 5.0 +/- 1.2 ng x kg(-1) x min(-1) to a peak of 14.2 +/- 2.8 ng x kg(-1) x min(-1) at 15 min of exercise. These results show that 1) approximately two- and threefold increases in NHS and hepatic NE spillover occur during heavy exercise, demonstrating that sympathetic drive to these tissues contributes to the increase in circulating NE; 2) the high catecholamine FX by the NHS tissues results in an Epi level at the liver that is considerably lower than that in the arterial blood; and 3) circulating NE delivery to the liver is sustained despite high catecholamine FX due to simultaneous NHS NE release.
Authors:
R H Coker; M G Krishna; D B Lacy; E J Allen; D H Wasserman
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  82     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1997 Apr 
Date Detail:
Created Date:  1997-06-26     Completed Date:  1997-06-26     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1244-9     Citation Subset:  IM    
Affiliation:
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA. cokerrh@ctrvax.vanderbilt.edu
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MeSH Terms
Descriptor/Qualifier:
Animals
Dogs
Epinephrine / blood,  metabolism
Heart Rate / physiology
Hepatic Artery / physiology
Liver / innervation*,  metabolism
Liver Circulation / physiology
Norepinephrine / blood,  metabolism
Physical Exertion / physiology*
Portal Vein / physiology
Splanchnic Nerves / physiology*
Sympathetic Nervous System / physiology*
Grant Support
ID/Acronym/Agency:
R01-DK-50277/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
51-41-2/Norepinephrine; 51-43-4/Epinephrine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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