Christine Des Rosiers

Montreal Heart Institute, Montréal, Quebec, Canada

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Publications (120)473.52 Total impact

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    ABSTRACT: Heart disease remains a major complication of diabetes and identification of new therapeutic targets is essential. This study investigates the role of the protein kinase MK2, a p38MAPK downstream target, in the development of diabetes-induced cardiomyopathy. Diabetes was induced in control (MK2(+/+)) and MK2 null (MK2(-/-)) mice using repeated injections of a low dose of streptozotocin (STZ). This protocol generated in MK2(+/+) mice, a model of diabetes characterized by a 50% decrease in plasma insulin, hyperglycemia, insulin resistance (IR) as well as major contractile dysfunction, which was associated with alterations in proteins involved in calcium handling. While MK2(-/-)-STZ mice remained hyperglycemic, they showed improved IR and none of the cardiac functional or molecular alterations. Further analyses highlighted marked lipid perturbations in MK2(+/+)-STZ mice, which encompass increased (i) circulating levels of free fatty acid, ketone bodies and long chain acylcarnitines, as well as (ii) cardiac triglyceride accumulation and ex vivo palmitate β-oxidation. MK2(-/-)-STZ mice were also protected against all these diabetes-induced lipid alterations. Our results demonstrate the benefits of MK2 deletion on diabetes-induced cardiac molecular and lipid metabolic changes as well as contractile dysfunction. As a result, MK2 represents a new potential therapeutic target to prevent diabetes-induced cardiac dysfunction.
    Diabetes 11/2015; DOI:10.2337/db15-0238 · 8.10 Impact Factor
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    ABSTRACT: Objective: Proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes the degradation of the low-density lipoprotein receptor thereby elevating plasma low-density lipoprotein cholesterol levels and the risk of coronary heart disease. Thus, the use of PCSK9 inhibitors holds great promise to prevent heart disease. Previous work found that PCSK9 is involved in triglyceride metabolism, independently of its action on low-density lipoprotein receptor, and that other yet unidentified receptors could mediate this effect. Therefore, we assessed whether PCSK9 enhances the degradation of CD36, a major receptor involved in transport of long-chain fatty acids and triglyceride storage. Approach and results: Overexpressed or recombinant PCSK9 induced CD36 degradation in cell lines and primary adipocytes and reduced the uptake of the palmitate analog Bodipy FL C16 and oxidized low-density lipoprotein in 3T3-L1 adipocytes and hepatic HepG2 cells, respectively. Surface plasmon resonance, coimmunoprecipitation, confocal immunofluorescence microscopy, and protein degradation pathway inhibitors revealed that PCSK9 directly interacts with CD36 and targets the receptor to lysosomes through a mechanism involving the proteasome. Importantly, the level of CD36 protein was increased by >3-fold on small interfering RNA knockdown of endogenous PCSK9 in hepatic cells and similarly increased in the liver and visceral adipose tissue of Pcsk9(-/-) mice. In Pcsk9(-/-) mice, increased hepatic CD36 was correlated with an amplified uptake of fatty acid and accumulation of triglycerides and lipid droplets. Conclusions: Our results demonstrate an important role of PCSK9 in modulating the function of CD36 and triglyceride metabolism. PCSK9-mediated CD36 degradation may serve to limit fatty acid uptake and triglyceride accumulation in tissues, such as the liver.
    Arteriosclerosis Thrombosis and Vascular Biology 10/2015; DOI:10.1161/ATVBAHA.115.306032 · 6.00 Impact Factor
  • Matthieu Ruiz · Roselle Gélinas · Fanny Vaillant · Benjamin Lauzier · Christine Des Rosiers ·
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    ABSTRACT: There has been a resurgence of interest for the field of cardiac metabolism catalyzed by evidence demonstrating a role of metabolic dysregulation in the pathogenesis of heart disease as well as the increased need for new therapeutic targets for patients with these diseases. In this regard, measuring substrate fluxes is critical in providing insight into the dynamics of cellular metabolism and in delineating the regulation of metabolite production and utilization. This chapter provides a comprehensive description of concepts, guidelines, and tips to assess metabolic fluxes relevant to energy substrate metabolism using (13)C-labeled substrates and (13)C-isotopomer analysis by gas chromatography-mass spectrometry (GC-MS), and the ex vivo working heart as study model. The focus will be on the mouse and on flux parameters, which are commonly assessed in the field, namely, those relevant to substrate selection for energy metabolism, specifically the relative contribution of carbohydrate (glucose, lactate, and pyruvate) and fatty acid oxidation to acetyl-CoA formation for citrate synthesis, glycolysis, as well as anaplerosis. We provide detailed procedures for the heart isolation and perfusion in the working mode as well as for sample processing for metabolite extraction and analysis by GC-MS and subsequent data processing for calculation of metabolic flux parameters. Finally, we address practical considerations and discuss additional applications and future challenges.
    Methods in enzymology 09/2015; 561:107-47. DOI:10.1016/bs.mie.2015.06.026 · 2.09 Impact Factor
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    ABSTRACT: Nutritional energy support during extracorporeal membrane oxygenation (ECMO) should promote successful myocardial adaptation and eventual weaning from the ECMO circuit. Fatty acids (FAs) are a major myocardial energy source, and medium-chain FAs (MCFAs) are easily taken up by cell and mitochondria without membrane transporters. Odd-numbered MCFAs supply carbons to the citric acid cycle (CAC) via anaplerotic propionyl-CoA as well as acetyl-CoA, the predominant beta-oxidation product for even-numbered MCFA. Theoretically, this anaplerotic pathway enhances carbon entry into the CAC, and provides superior energy state and preservation of protein synthesis. We tested this hypothesis in an immature swine model undergoing ECMO. Fifteen male Yorkshire pigs (26-45 days old) with 8-hour ECMO received either normal saline, heptanoate (odd-numbered MCFA) or octanoate (even-numbered MCFA) at 2.3 μmol/kg body wt/min as MCFAs systemically during ECMO (n = 5 per group). The 13-Carbon ((13)C)-labeled substrates ([2-(13)C]lactate, [5,6,7-(13)C3]heptanoate and [U-(13)C6]leucine) were systemically infused as metabolic markers for the final 60 minutes before left ventricular tissue extraction. Extracted tissues were analyzed for the (13)C-labeled and absolute concentrations of metabolites by nuclear magnetic resonance and gas chromatography-mass spectrometry. Octanoate produced markedly higher myocardial citrate concentration, and led to a higher [ATP]/[ADP] ratio compared with other groups. Unexpectedly, octanoate as well as heptanoate increased the flux of propionyl-CoA relative to acetyl-CoA into the CAC compared to control. MCFAs promoted increases in leucine oxidation, but were not associated with a difference in protein synthesis rate. In conclusion, octanoate provides energetic advantages to the heart over heptanoate. Copyright © 2015, American Journal of Physiology - Heart and Circulatory Physiology.
    AJP Heart and Circulatory Physiology 07/2015; 309(7):ajpheart.00298.2015. DOI:10.1152/ajpheart.00298.2015 · 3.84 Impact Factor
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    ABSTRACT: Over consumption of dietary fat is increasingly linked with motivational and emotional impairments. Human and animal studies demonstrate associations between obesity and blunted reward function at the behavioral and neural level, but it is unclear to what degree such changes are a consequence of an obese state and whether they are contingent on dietary lipid class. We sought to determine the impact of prolonged ad libitum intake of diets rich in saturated or monounsaturated fat, separate from metabolic signals associated with increased adiposity, on dopamine (DA)-dependent behaviors and to identify pertinent signaling changes in the nucleus accumbens (NAc). Male rats fed a saturated (palm oil), but not an isocaloric monounsaturated (olive oil), high-fat diet exhibited decreased sensitivity to the rewarding (place preference) and locomotor-sensitizing effects of amphetamine as compared to low-fat diet controls. Blunted amphetamine action by saturated high-fat feeding was entirely independent of caloric intake, weight gain and plasma levels of leptin, insulin and glucose and was accompanied by biochemical and behavioral evidence of reduced D1R signaling in the NAc. Saturated high-fat feeding was also tied to protein markers of increased AMPA receptor mediated plasticity and decreased DA transporter expression in the NAc but not to alterations in DA turnover and biosynthesis. Collectively, the results suggest that intake of saturated lipids can suppress DA signaling apart from increases in body weight and adiposity-related signals known to affect mesolimbic DA function, in part by diminishing D1 receptor signaling, and that equivalent intake of monounsaturated dietary fat protects against such changes.Neuropsychopharmacology accepted article preview online,
    Neuropsychopharmacology 07/2015; DOI:10.1038/npp.2015.207 · 7.05 Impact Factor

  • Archives of Cardiovascular Diseases Supplements 04/2015; 7(2). DOI:10.1016/S1878-6480(15)30022-7
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    ABSTRACT: Extracorporeal membrane oxygenation (ECMO) provides mechanical circulatory support for infants and children with postoperative cardiopulmonary failure. Nutritional support is mandatory during ECMO, although specific actions for substrates on the heart have not been delineated. Prior work shows that enhancing pyruvate oxidation promotes successful weaning from ECMO. Accordingly, we tested the hypothesis that prolonged systemic pyruvate supplementation activates pyruvate oxidation in an immature swine model in vivo. Twelve male mixed breed Yorkshire piglets (age 30-49 days) received systemic infusion of either normal saline (Group C) or pyruvate (Group P) during the final 6 hours of 8 hours of ECMO. Over the final hour piglets received [2-(13)C] Pyruvate, as a reference substrate for oxidation, and [(13)C6]-L-leucine, as an indicator for amino acid oxidation and protein synthesis. A significant increase in lactate and pyruvate concentrations occurred, along with an increase in the absolute concentration of the CAC intermediates. An increase in anaplerotic flux through pyruvate carboxylation in group P occurred compared to no change in pyruvate oxidation. Additionally, pyruvate promoted an increase in the phosphorylation state of several nutrient sensitive enzymes, like AMPK and ACC, suggesting activation for fatty acid oxidation. Pyruvate also promoted O-GlcNAcylation through the hexosamine biosynthetic pathway (HBP). In conclusion, although prolonged pyruvate supplementation did not alter pyruvate oxidation, it did elicit changes in nutrient and energy sensitive pathways. Therefore, the observed results support the further study of pyruvate and its downstream effect on cardiac function. Copyright © 2015, American Journal of Physiology - Heart and Circulatory Physiology.
    AJP Heart and Circulatory Physiology 04/2015; 309(1):ajpheart.00011.2015. DOI:10.1152/ajpheart.00011.2015 · 3.84 Impact Factor

  • Archives of Cardiovascular Diseases Supplements 04/2015; 7(2):185. DOI:10.1016/S1878-6480(15)30148-8
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    V. Turcot · J. Brunet · C. Daneault · J. C. Tardif · C. Des Rosiers · G. Lettre ·
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    ABSTRACT: Background To improve the prevention, treatment and risk prediction of cardiovascular diseases, genetic markers and gene–diet interactions are currently being investigated. The Montreal Heart Institute (MHI) Biobank is suitable for such studies because of its large sample size (currently, n = 17 000), the availability of biospecimens, and the collection of data on dietary intakes of saturated (SFAs) and n-3 and n-6 polyunsaturated (PUFAs) fatty acids estimated from a 14-item food frequency questionnaire (FFQ). We tested the validity of the FFQ by correlating dietary intakes of these fatty acids with their red blood cell (RBC) content in MHI Biobank participants.Methods Seventy-five men and 75 women were selected from the Biobank. We successfully obtained RBC fatty acids for 142 subjects using gas chromatography coupled to mass spectrometry. Spearman correlation coefficients were used to test whether SFA scores and daily intakes (g day−1) of n-3 and n-6 PUFAs correlate with their RBC content.ResultsBased on covariate-adjusted analyses, intakes of n-3 PUFAs from vegetable sources were significantly correlated with RBC α-linolenic acid levels (ρ = 0.23, P = 0.007), whereas n-3 PUFA intakes from marine sources correlated significantly with RBC eicosapentaenoic acid (ρ = 0.29, P = 0.0008) and docosahexaenoic acid (ρ = 0.41, P = 9.2 × 10–7) levels. Intakes of n-6 PUFAs from vegetable sources correlated with RBC linoleic acid (ρ = 0.18, P = 0.04). SFA scores were not correlated with RBC total SFAs.Conclusions The MHI Biobank 14-item FFQ can appropriately estimate daily intakes of n-3 PUFAs from vegetable and marine sources, as well as vegetable n-6 PUFAs, which enables the possibility of using these data in future studies.
    Journal of Human Nutrition and Dietetics 09/2014; DOI:10.1111/jhn.12272 · 1.99 Impact Factor
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    ABSTRACT: Background Angiopoietin‐like‐2 (angptl2) is produced by several cell types including endothelial cells, adipocytes and macrophages, and contributes to the inflammatory process in cardiovascular diseases. We hypothesized that angptl2 impairs endothelial function, and that lowering angptl2 levels protects the endothelium against high‐fat diet (HFD)‐induced fat accumulation and hypercholesterolemia. Methods and Results Acute recombinant angptl2 reduced (P<0.05) acetylcholine‐mediated vasodilation of isolated wild‐type (WT) mouse femoral artery, an effect reversed (P<0.05) by the antioxidant N‐acetylcysteine. Accordingly, in angptl2 knockdown (KD) mice, ACh‐mediated endothelium‐dependent vasodilation was greater (P<0.05) than in WT mice. In arteries from KD mice, prostacyclin contributed to the overall dilation unlike in WT mice. After a 3‐month HFD, overall vasodilation was not altered, but dissecting out the endothelial intrinsic pathways revealed that NO production was reduced in arteries isolated from HFD‐fed WT mice (P<0.05), while NO release was maintained in KD mice. Similarly, endothelium‐derived hyperpolarizing factor (EDHF) was preserved in mesenteric arteries from HFD‐fed KD mice but not in those from WT mice. Finally, the HFD increased (P<0.05) total cholesterol–to–high‐density lipoprotein ratios, low‐density lipoprotein–to–high‐density lipoprotein ratios, and leptin levels in WT mice only, while glycemia remained similar in the 2 strains. KD mice displayed less triglyceride accumulation in the liver (P<0.05 versus WT), and adipocyte diameters in mesenteric and epididymal white adipose tissues were smaller (P<0.05) in KD than in WT fed an HFD, while inflammatory gene expression increased (P<0.05) in the fat of WT mice only. Conclusions Lack of angptl2 expression limits the metabolic stress induced by an HFD and maintains endothelial function in mice.
    Journal of the American Heart Association 06/2014; 3(4):e001024-e001024. DOI:10.1161/JAHA.114.001024 · 4.31 Impact Factor
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    ABSTRACT: Background It was demonstrated that branched-chain amino acids like leucine induce insulin resistance in muscle and adipose tissues. The mechanism proposed to explain leucine action involves mTOR/p70S6K signaling. This pathway can be activated by leucine and is implicated in the stimulation of an insulin negative feedback loop. Knowing that insulin-resistance participates in diabetic cardiomyopathy, we were interested in studying leucine effect in cardiomyocytes. Methods Primary cultured adult rat cardiomyocytes were pretreated with different concentrations of leucine (from 1 to 10 mM) during different periods of time (up to 20h) before being exposed to insulin (3x10−9 M, 30 min). Results In absence of leucine, insulin induced a 6-fold increase in glucose uptake (0.31+/−0.04 vs. 0.05+/−0.01 μmoles/mg.h). This correlated with the increase in phosphorylation state of PKB and AS160, both known to regulate glucose transport downstream of insulin. Pre-incubation with leucine for 1 h stimulated mTOR/p70S6K pathway resulting in the inhibiting phosphorylation of IRS-1 located in the proximal insulin signaling pathway. This is accompanied by a significant decrease in PKB and AS160 phosphorylation but, surprisingly, insulin-stimulated glucose uptake was preserved (0.31+/–0.05 μmoles/mg.h). On the other hand, a longer incubation (14h) with leucine induced a drastic decrease in glucose transport (0.056+/–0.01 μmoles/mg.h). The mTOR/p70S6K inhibitor rapamycin did not prevent this inhibition. Moreover, the non-metabolized leucine analog BCH was able to stimulate mTOR/p70S6K pathway but had no effect on the insulin-mediated stimulation of glucose uptake. By contrast, intermediates of leucine catabolism, alpha-ketoisocaproate, acetoacetate and betahydroxybutyrate, inhibited glucose uptake similarly to leucine. Conclusion Leucine catabolism reduces insulin-dependent glucose transport independently of insulin signaling.
    Archives of Cardiovascular Diseases Supplements 04/2014; 6:13. DOI:10.1016/S1878-6480(14)71296-0
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    ABSTRACT: Extracorporeal membrane oxygenation (ECMO) provides a bridge to recovery after myocardial injury in infants and children, yet morbidity and mortality remain high. Weaning from the circuit requires adequate cardiac contractile function, which can be impaired by metabolic disturbances induced either by ischemia-reperfusion and/or by ECMO. We tested the hypothesis that although ECMO partially ameliorates metabolic abnormalities induced by ischemia-reperfusion, these abnormalities persist or recur with weaning. We also determined if thyroid hormone supplementation (triiodothyronine) during ECMO improves oxidative metabolism and cardiac function. Neonatal piglets underwent transient coronary ischemia to induce cardiac injury then were separated into 4 groups based on loading status. Piglets without coronary ischemia served as controls. We infused into the left coronary artery [2-(13)C]pyruvate and [(13)C6, (15)N]l-leucine to evaluate oxidative metabolism by gas chromatography-mass spectroscopy and nuclear magnetic resonance methods. ECMO improved survival, increased oxidative substrate contribution through pyruvate dehydrogenase, reduced succinate and fumarate accumulation, and ameliorated ATP depletion induced by ischemia. The functional and metabolic benefit of ECMO was lost with weaning, yet triiodothyronine supplementation during ECMO restored function, increased relative pyruvate dehydrogenase flux, reduced succinate and fumarate, and preserved ATP stores. Although ECMO provides metabolic rest by decreasing energy demand, metabolic impairments persist, and are exacerbated with weaning. Treating ECMO-induced thyroid depression with triiodothyronine improves substrate flux, myocardial oxidative capacity and cardiac contractile function. This translational model suggests that metabolic targeting can improve weaning.
    Journal of the American Heart Association 03/2014; 3(2):e000680. DOI:10.1161/JAHA.113.000680 · 4.31 Impact Factor

  • Diabetes & Metabolism 03/2014; 40:A65. DOI:10.1016/S1262-3636(14)72444-9 · 3.27 Impact Factor
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    ABSTRACT: Anesthetics used in infants and children are implicated in the development of neurocognitive disorders. Although propofol induces neuroapoptosis in developing brain, the underlying mechanisms require elucidation and may have an energetic basis. We studied substrate utilization in immature swine anesthetized with either propofol or isoflurane for 4 hours. Piglets were infused with 13-Carbon-labeled glucose and leucine in the common carotid artery to assess citric acid cycle (CAC) metabolism in the parietal cortex. The anesthetics produced similar systemic hemodynamics and cerebral oxygen saturation by near-infrared spectroscopy. Compared with isoflurane, propofol depleted ATP and glycogen stores. Propofol decreased pools of the CAC intermediates, citrate, and α-ketoglutarate, while markedly increasing succinate along with decreasing mitochondrial complex II activity. Propofol also inhibited acetyl-CoA entry into the CAC through pyruvate dehydrogenase, while promoting glycolytic flux with marked lactate accumulation. Although oxygen supply appeared similar between the anesthetic groups, propofol yielded a metabolic phenotype that resembled a hypoxic state. Propofol impairs substrate flux through the CAC in the immature cerebral cortex. These impairments occurred without systemic metabolic perturbations that typically accompany propofol infusion syndrome. These metabolic abnormalities may have a role in the neurotoxity observed with propofol in the vulnerable immature brain.Journal of Cerebral Blood Flow & Metabolism advance online publication, 8 January 2014; doi:10.1038/jcbfm.2013.229.
    Journal of cerebral blood flow and metabolism: official journal of the International Society of Cerebral Blood Flow and Metabolism 01/2014; 34(3). DOI:10.1038/jcbfm.2013.229 · 5.41 Impact Factor
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    ABSTRACT: Objective Measurements of oxidative stress biomarkers in patients with heart failure (HF) have yielded controversial results. This study aimed at testing the hypothesis that circulating levels of the lipid peroxidation product 4-hydroxynonenal bound to thiol proteins (4HNE-P) are strongly associated with those of its potential precursors, namely n-6 polyunsaturated fatty acids (PUFA).Methods & ResultsCirculating levels of 4HNE-P were evaluated by gas chromatography-mass spectrometry in 71 control subjects and 61 ambulatory symptomatic HF patients along with various other clinically- and biochemically-relevant parameters, including other oxidative stress markers, and total levels of fatty acids from all classes, which reflect both free and bound to cholesterol, phospholipids and triglycerides. All HF patients had severe systolic functional impairment despite receiving optimal evidence-based therapies. Compared to controls, HF patients displayed markedly lower circulating levels of HDL- and LDL-cholesterol, which are major PUFA carriers, as well as of PUFA of the n-6 series, specifically linoleic acid (LA; P=0.001). Circulating 4HNE-P in HF patients was similar to controls, albeit multiple regression analysis revealed that LA was the only factor that was significantly associated with circulating 4HNE-P in the entire population (R2=0.086; P=0.02). In HF patients only, 4HNE-P was even more strongly associated with LA (P=0.003) and HDL-cholesterol (p<0.0002). Our results demonstrate that 4HNE-P levels, expressed relative to HDL-cholesterol, increase as HDL-cholesterol plasma levels decrease in the HF group only.Conclusion Results from this study emphasize the importance of considering changes in lipids and lipoproteins in the interpretation of measurements of lipid peroxidation products. Further studies appear warranted to explore the possibility that HDL-cholesterol particles may be a carrier of 4HNE adducts.
    12/2013; 2(1). DOI:10.1016/j.redox.2013.12.009
  • Gary D Lopaschuk · Kara Hansell-Keehan · Heinrich Taegtmeyer · Christine Des Rosiers ·
    AJP Heart and Circulatory Physiology 12/2013; 306(2). DOI:10.1152/ajpheart.00938.2013 · 3.84 Impact Factor
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    ABSTRACT: Aim: In mice, genetic background is known to influence various parameters, including cardiac function. Its impact on cardiac energy substrate metabolism - a factor known to be closely related to function and contributes to disease development - is, however, unclear. This was examined in this study. Methods & Results: In commonly-used control mouse substrains SJL/JCrNTac, 129S6/SvEvTac, C57Bl/6J and C57Bl/6NCrl, we assessed the functional and metabolic phenotypes of 3 month old working mouse hearts perfused ex vivo with physiological concentrations of 13C labeled carbohydrates (CHO) and a fatty acid (FA). Marked variations in various functional and metabolic flux parameters were observed among all mouse substrains, although the pattern observed differed for these parameters. For example, among all strains, C57Bl/6NCrl hearts had a greater cardiac output (+1.7 fold vs SJL/JCrNTac and C57Bl/6J; P<0.05), while at the metabolic level, 129S6/SvEvTac hearts stood out by displaying (vs. all 3 strains) a striking shift from exogenous FA (~ -3.5-fold) to CHO oxidation as well as increased glycolysis (+1.7-fold) and FA incorporation into triglycerides (+2-fold). Correlation analyses revealed, however, specific linkages between glycolysis, FA oxidation and pyruvate metabolism and cardiac work, oxygen consumption with heart rate, respectively. This implies that any genetically-determined factors affecting a given metabolic flux parameter may impact on the associated functional parameters. Conclusion: Our results emphasize the importance of selecting the appropriate control strain for cardiac metabolic studies using transgenic mice, a factor that has often been neglected. Understanding the molecular mechanisms underlying the diversity of strain-specific cardiac metabolic and functional profiles, particularly the 129S6/SvEvTac, may ultimately disclose new specific metabolic targets for interventions in heart disease.
    AJP Heart and Circulatory Physiology 11/2013; 306(1). DOI:10.1152/ajpheart.00465.2013 · 3.84 Impact Factor
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    ABSTRACT: Purpose Extracorporeal membrane oxygenation (ECMO) is increasingly used as a rescue technique for cardiopulmonary support in infants and children for a wide range of clinical scenarios. However, morbidity and mortality remains high and is directly proportional to duration of use. Prior work has shown that ECMO causes hormone and metabolic disturbances which may be counterproductive to recovery after critical illness. Therefore, we developed a model of cardiac injury rescued by ECMO. We hypothesized that supplementing triiodothyronine (T3) would facilitate weaning from ECMO by improving substrate utilization and citric acid cycle (CAC) flux. Methods Twenty-two neonatal piglets underwent transient coronary ischemia to induce cardiac injury. They were then separated into 4 groups based on loading status: normal circulation (LOAD), 8 hours of ECMO (UNLOAD), post-wean from ECMO (RELOAD), and post-wean from ECMO with T3 supplementation (RELOAD + T3). We infused [2-13C]-pyruvate as an oxidative substrate into the coronary circulation. Gas chromatography / mass spectroscopy (GCMS) and nuclear magnetic resonance (NMR) traced substrates through oxidative metabolism. Results ECMO depressed circulating T3 levels to 35% of baseline at 8 hours. LOAD decreased systolic function which did not recover after ECMO support (RELOAD). T3 supplementation restored systolic function to above baseline values without increasing myocardial oxygen consumption reflecting increased cardiac efficiency. Both LOAD and RELOAD increased accumulation of pyruvate, lactate and CAC intermediates indicative of metabolic block. However, ECMO +T3 decreased pyruvate (p=0.02) and lactate (p=0.02) accumulation and increased the oxidative flux through pyruvate dehydrogenase (p=0.04). NMR confirmed increased pyruvate entry into the CAC with T3 supplementation (p=0.05). Conclusion T3 supplementation promotes cardiac oxidative metabolism during weaning from ECMO by removing a metabolic block at the level of pyruvate dehydrogenase and increasing CAC flux. This translates to improved cardiac efficiency during critical illness. These findings indicate that T3 depression during ECMO support is maladaptive and that supplementation may serve as therapeutic agent for children with refractory heart failure. Future work will investigate the acute mechanisms of T3 on neonatal myocardial metabolism.
    2013 American Academy of Pediatrics National Conference and Exhibition; 10/2013
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    ABSTRACT: Marine n-3 polyunsaturated fatty acids alter cardiac phospholipids and prevent cardiac pathology in rodents subjected to pressure overload. This approach has not been evaluated in humans or large animals with hypertension-induced pathological hypertrophy. We evaluated docosahexaenoic acid (DHA) in old female dogs with hypertension caused by 16 weeks of aldosterone infusion. Aldosterone-induced hypertension resulted in concentric left ventricular (LV) hypertrophy and impaired diastolic function in placebo-treated dogs. DHA supplementation increased DHA and depleted arachidonic acid in cardiac phospholipids, but did not improve LV parameters compared to placebo. Surprisingly, DHA significantly increased serum aldosterone concentration and blood pressure compared to placebo. Cardiac mitochondrial yield was decreased in placebo-treated hypertensive dogs compared to normal animals, which was prevented by DHA. Extensive analysis of mitochondrial function found no differences between DHA and placebo groups. In conclusion, DHA did not favorably impact mitochondrial or LV function in aldosterone hypertensive dogs.
    Journal of Cardiovascular Translational Research 09/2013; 6(6). DOI:10.1007/s12265-013-9511-y · 3.02 Impact Factor
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    ABSTRACT: Supplementation with the n3 polyunsaturated fatty acid docosahexaenoic acid (DHA) is beneficial in heart failure patients, however the mechanisms are unclear. DHA is incorporated into membrane phospholipids, which may prevent mitochondrial dysfunction. Thus we assessed the effects of DHA supplementation on cardiac mitochondria and the development of heart failure caused by aortic pressure overload. Pathological cardiac hypertrophy was generated in rats by thoracic aortic constriction. Animals were fed either a standard diet or were supplemented with DHA (2.3 % of energy intake). After 14 weeks, heart failure was evident by left ventricular hypertrophy and chamber enlargement compared to shams. Left ventricle fractional shortening was unaffected by DHA treatment in sham animals (44.1 ± 1.6 % vs. 43.5 ± 2.2 % for standard diet and DHA, respectively), and decreased with heart failure in both treatment groups, but to a lesser extent in DHA treated animals (34.9 ± 1.7 %) than with the standard diet (29.7 ± 1.5 %, P < 0.03). DHA supplementation increased DHA content in mitochondrial phospholipids and decreased membrane viscosity. Myocardial mitochondrial oxidative capacity was decreased by heart failure and unaffected by DHA. DHA treatment enhanced Ca(2+) uptake by subsarcolemmal mitochondria in both sham and heart failure groups. Further, DHA lessened Ca(2+)-induced mitochondria swelling, an index of permeability transition, in heart failure animals. Heart failure increased hydrogen peroxide-induced mitochondrial permeability transition compared to sham, which was partially attenuated in interfibrillar mitochondria by treatment with DHA. DHA decreased mitochondrial membrane viscosity and accelerated Ca(2+) uptake, and attenuated susceptibility to mitochondrial permeability transition and development of left ventricular dysfunction.
    Cardiovascular Drugs and Therapy 09/2013; 27(6). DOI:10.1007/s10557-013-6487-4 · 3.19 Impact Factor

Publication Stats

3k Citations
473.52 Total Impact Points


  • 2006-2015
    • Montreal Heart Institute
      Montréal, Quebec, Canada
  • 1988-2015
    • Université de Montréal
      • • Montreal Heart Institute
      • • Department of Nutrition
      Montréal, Quebec, Canada
  • 2013
    • Université du Québec à Montréal
      Montréal, Quebec, Canada
  • 2001-2008
    • McGill University
      • • Division of Experimental Medicine
      • • Respiratory Division
      Montréal, Quebec, Canada
  • 1989-2005
    • Case Western Reserve University
      • School of Medicine
      Cleveland, Ohio, United States
  • 2001-2002
    • George Washington University
      Washington, Washington, D.C., United States
  • 1987
    • Massachusetts Institute of Technology
      Cambridge, Massachusetts, United States