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This Article Full Text Full Text (PDF) All Versions of this Article: 288/1/E246    most recent 00211.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (15) Citing Articles via Google Scholar Google Scholar Articles by An, D. Articles by Rodrigues, B. Search for Related Content PubMed PubMed Citation Articles by An, D. Articles by Rodrigues, B.

The metabolic "switch" AMPK regulates cardiac heparin-releasable lipoprotein lipase

Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, Canada

Submitted 20 May 2004 ; accepted in final form 18 August 2004

The "fuel gauge" AMP-activated protein kinase (AMPK) facilitates ATP production to meet energy demands during metabolic stress. Given the importance of lipoprotein lipase (LPL) in providing hearts with fatty acids (FA), the preferred substrate consumed by the heart, the objective of the present study was to investigate whether activation of AMPK influences LPL at its functionally relevant location, the coronary lumen. Hearts from overnight-fasted rats were first perfused with heparin to release LPL, and homogenates from these hearts were then used to measure total and phospho-AMPK- by Western blotting. Manipulation of AMPK activity [with drugs like adenine 9--D-arabinofuranoside (Ara-A) and insulin (that inhibit) or perhexiline and oligomycin (that stimulate)] and its influence on LPL was also determined. Fasting augmented the activity of both AMPK and luminal LPL on immediate removal of hearts, effects that still remained even after in vitro perfusion of hearts for 1 h. Inhibition of AMPK in fasted hearts using an inhibitor like Ara-A or through provision of insulin markedly lowered the enhanced luminal LPL activity. In contrast, AMPK activators, like perhexiline and oligomycin, produced a significant elevation in heparin-releasable LPL activity. Thus, with fasting or drugs that influence AMPK, a strong correlation between this metabolic switch and cardiac LPL activity was established. Our data suggest that, in addition to its direct role in promoting FA oxidation, AMPK-mediated recruitment of LPL to the coronary lumen could represent an immediate compensatory response by the heart to guarantee FA supply.

isolated hearts; fasting; cardiac metabolism; palmitoyltransferase-1; adenosine 5'-triphosphate; adenosine 5'-triphosphate-activated protein kinase

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