Metabolism of lipoprotein lipid in the isolated perfused rat heart

Delcher, Harry K.; Fried, Melvin; Shipp, Joseph C.

doi:10.1016/0005-2760(65)90090-1

Cited by 31 publications

(14 citation statements)

References 20 publications

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“…Significant cardiac utilisation of d<1.006 lipoprotein-TAG (CM) was also found in isolated rat heart [9] TAG oxidation accounted for 40% of CO 2 production (equivalent to that of NEFA oxidation) [10] (and in broad agreement with earlier studies [11]). Further evidence for a role for…”

Section: Accepted Manuscriptsupporting

confidence: 85%

The role of triacylglycerol in cardiac energy provision

Evans

Hui‐Kang

2016

Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biolog

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Triacylglycerols (TAG) constitute the main energy storage resource in mammals, by virtue of their high energy density. This in turn is a function of their highly reduced state and hydrophobicity.Limited water solubility, however, imposes specific requirements for delivery and uptake mechanisms on TAG-utilising tissues, including the heart, as well as intracellular disposition. TAGs constitute potentially the major energy supply for working myocardium, both through bloodborne provision and as intracellular TAG within lipid droplets, but also provide the heart with fatty acids (FA) which the myocardium cannot itself synthesise but are required for glycerolipid derivatives with (non-energetic) functions, including membrane phospholipids and lipid signalling molecules. Furthermore they serve to buffer potentially toxic amphipathic fatty acid derivatives.Intracellular handling and disposition of TAGs and their FA and glycerolipid derivatives similarly requires dedicated mechanisms in view of their hydrophobic character. Dysregulation of utilisation can result in inadequate energy provision, accumulation of TAG and/or esterified species, and these may be responsible for significant cardiac dysfunction in a variety of disease states. This review will focus on the role of TAG in myocardial energy provision, by providing FAs from exogenous and endogenous TAG sources for mitochondrial oxidation and ATP production, and how this can change in disease and impact on cardiac function. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 3Key words:heart; triacylglycerol; very-low-density lipoprotein; VLDL; chylomicron; lipid droplet Highlights: Triacylglycerols are supplied to the myocardium within chylomicrons and VLDL  Heart assimilates triacylglycerol-rich lipoproteins by LPL and receptor-mediated routes  Exogenous triacylglycerol-derived fatty acids enter an intracellular lipid pool  Intracardiac triacylglycerol is an important source of fatty acids for oxidation  Dysregulation of triacylglycerol metabolism is associated with cardiac dysfunction

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Section: Accepted Manuscriptsupporting

confidence: 85%

The role of triacylglycerol in cardiac energy provision

Evans

Hui‐Kang

2016

Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biolog

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“…This possibility receives support from work in the perfused rat heart (35) showing an increase in FFA in the perfusate during perfusion with low density lipoproteins (d < 1.006). That the human heart has the capacity to hydrolyze circulating triglycerides is strongly suggested by the recent demonstration in vivo of the presence of heparin-releasable lipoprotein lipase from the human heart (36).…”

Section: Discussionmentioning

confidence: 90%

Free fatty acid metabolism of the human heart at rest

Most¹,

Brachfeld²,

Gorlin³

et al. 1969

J. Clin. Invest.

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A B S T R A C T Myocardial substrate metabolism was studied in 13 subjects at the time of diagnostic cardiac catheterization by means of palmitic acid-14C infusion with arterial and coronary sinus sampling. Two subjects were considered free of cardiac pathology and all, with one exception, demonstrated lactate extraction across the portion of heart under study. Data for this single lactate-producing subject were treated separately.The fractional extraction of '4C-labeled free fatty acids (FFA) (44.4+±9.5%) was nearly twice that of unlabeled FFA (23.2 ±7.8%) and raised the possibility of release of FFA into the coronary sinus. FFA uptake, based on either the arterial minus coronary sinus concentration difference or the FFA-14C fractional extraction, was directly proportional to the arterial FFA concentration. Gas-liquid chromatography failed to demonstrate selective handling of any individual FFA by the heart. Fractional oxidation of FFA was 53.5 ±+12.7%, accounting for 53.2 ±14.4% of the heart's oxygen consumption while nonlipid substrates accounted for an additional 30.0 ±17.3%. Determinations of both labeled and unlabeled triglycerides suggested utilization of this substrate by the fasting human heart. Direct measurement of FFA fractional oxidation as well as FFA uptake, exclusive of possible simultaneous FFA release, would appear necessary in studies concerned with human myocardial FFA metabolism.

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“…Swan (13) reported that in the frog muscle, lowering of the external pH brought about the loss of the superficially bound calcium. It was also reported that an acid extracellular pH decreased the glucose uptake in the rat heart (14). These findings cited above might explain some possible mechanism of the inhibition by low external pH or low concentration of sodium bicarbonate in the medium on the K-contracture, the phasic phase of which was said to be initiated by the released of tissue calcium (3)(4)(5) and the tonic phase diminished when external glucose was removed from the external medium (3), but no experimental evidence has been ob tained in the case of taenia coli.…”

Section: Sodium Phosphatementioning

confidence: 85%

Influences of External Magnesium, Bicarbonate and Phosphate on Potassium-Induced Contracture of the Guinea Pig Taenia Coli

Karaki

Urakawa

Ikeda

1966

Japanese Journal of Pharmacology

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It was reported that high-potassium (K) solution produced a contracture (K-induced contracture) in the guinea pig taenia coli, and the tension development in the muscle depolarized with high-K was dependent on calcium (1, 2), and that "Ca uptake and ex changeable fraction of cellular Ca increased with high-K (2).Furthermore, it was demonstrated that K-induced contracture was composed of phasic and tonic phases and was proposed that in the phasic contraction, sufficient calcium was released from a cellular site to initiate contraction, whereas in the tonic contraction, enough calcium crossed the membrane to initiate it and that the transmembrane calcium transport involved in the latter response was dependent on metabolism (3). On the basis of these results, the role of metabolism in the K-induced contracture of taenia coli was examined by the use of various metabolic intermediates, inhibitors of metabolism and active transport, revealing that the factors such as substrate removal, a decrease of tem perature, DNP, ouabain and a substitution of external sodium chloride with lithium chloride abolished the tonic response whereas the same factors had little or no effect on the phasic response.Hence it was considered that the phasic response was a passive process, while the tonic contraction was an active one depending on metabolism and possibly linked to active Na transport (4). This consideration was also supported by the electrophysiological experiments (5).In the present paper, further evidence was obtained concerning to the influences of the physiological components in the external media, that is, magnesium chloride (MgCl2), sodium bicarbonate (NaHCO3) and sodium phosphate (NaH2PO4) on the K-induced tension development of taenia coli. METHODSStrips of taenia coli (30-40 mg) were isolated from male guinea pigs weighing about 500 g. The excision of the muscle was endeavoured to avoid the Auerbach's plexus which includes the excitatory cholinergic nerve and intramural inhibitory nerve (6).

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Metabolism of lipoprotein lipid in the isolated perfused rat heart

Cited by 31 publications

References 20 publications

The role of triacylglycerol in cardiac energy provision

The role of triacylglycerol in cardiac energy provision

Free fatty acid metabolism of the human heart at rest

Influences of External Magnesium, Bicarbonate and Phosphate on Potassium-Induced Contracture of the Guinea Pig Taenia Coli

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