Document Detail

[11C]palmitate kinetics across the splanchnic bed in arterial, portal and hepatic venous plasma during fasting and euglycemic hyperinsulinemia.
MedLine Citation:
PMID:  16720244     Owner:  NLM     Status:  MEDLINE    
PURPOSE: The liver is fundamental in regulating lipid metabolism, and it supplies fatty acids (FA) to the rest of the body in the form of triglycerides (TG); the time-related relevance of this process is incompletely defined. The aim of the study was to investigate the appearance of labeled TG in the hepatic vascular bed after [11C]palmitate injection during fasting and insulin stimulation. METHODS: Plasma [11C]palmitate kinetics in arterial, portal and hepatic venous lipid fractions was studied in eight anesthetized pigs during fasting or euglycemic hyperinsulinemia. Plasma analyses were conducted at 10 and 40 min after tracer injection. Corresponding liver positron emission tomography (PET) images were acquired for the semiquantitative determination of hepatic FA uptake. RESULTS: At 10 min, plasma levels of unchanged [11C]palmitate were lower in hyperinsulinemic than in fasting experiments in the artery and in the portal vein (P< or=.03), suggesting faster clearance. Levels of unmetabolized [11C]palmitate did not differ between portal and arterial plasma. In the fasting state, a tendency to a positive arterial and portal vs. hepatic venous gradient was observed, indicative of net hepatic [11C]palmitate extraction. Labeled TG were already detectable at 10 min (fasting vs. hyperinsulinemia, ns) and were higher in fasting than in hyperinsulinemic animals at 40 min (92+/-1% and 82+/-6% of arterial plasma radioactivity). Higher proportions of labeled TG were recovered in portal vein plasma, suggesting release by the gut. The portal and the arterial-portal vs. hepatic venous TG gradient tended to be positive. Accordingly, hepatic FA uptake was higher, but declined more rapidly during fasting than during hyperinsulinemia. CONCLUSION: The study indicates that the redistribution of [11C]palmitate between different lipid pools occurs within the short time interval of most PET experiments and is strongly influenced by insulin. Labeled TG constitute an additional [11C]palmitate source in the modeling of PET data.
Letizia Guiducci; Mikko Järvisalo; Jan Kiss; Kjell Någren; Antti Viljanen; Alexandru G Naum; Amalia Gastaldelli; Timo Savunen; Juhani Knuuti; Piero A Salvadori; Ele Ferrannini; Pirjo Nuutila; Patricia Iozzo
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-05-02
Journal Detail:
Title:  Nuclear medicine and biology     Volume:  33     ISSN:  0969-8051     ISO Abbreviation:  Nucl. Med. Biol.     Publication Date:  2006 May 
Date Detail:
Created Date:  2006-05-24     Completed Date:  2006-08-31     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9304420     Medline TA:  Nucl Med Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  521-8     Citation Subset:  IM    
SSSUP Medical Sciences Branch, Pisa 56100, Italy; Turku PET Centre, University of Turku, Turku 20520, Finland.
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MeSH Terms
Carbon Radioisotopes / pharmacokinetics
Fasting / metabolism*
Glucose Clamp Technique
Hepatic Artery / metabolism
Hepatic Veins / metabolism
Hyperinsulinism / blood*
Liver / blood supply*,  metabolism*
Metabolic Clearance Rate
Palmitates / pharmacokinetics*
Portal System / metabolism*
Splanchnic Circulation*
Reg. No./Substance:
0/Carbon Radioisotopes; 0/Palmitates

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

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