Background Cardiac hypertrophy and heart failure are associated with metabolic dysregulation and a state of chronic energy deficiency. Although several disparate changes in individual metabolic pathways have been described, there has been no global assessment of metabolomic changes in hypertrophic and failing hearts in vivo. Here, we investigated the impact of pressure overload and infarction on myocardial metabolism. Methods and Results Male C57BL/6J mice were subjected to transverse aortic constriction (TAC) or permanent coronary occlusion (myocardial infarction; MI). A combination of LC/MS/MS and GC/MS techniques was used to measure 288 metabolites in these hearts. Both TAC and MI were associated with profound changes in myocardial metabolism affecting up to 40% of all metabolites measured. Prominent changes in branched amino acids acids (BCAAs) were observed after 1 week of TAC and 5 days after MI. Changes in BCAAs after MI were associated with myocardial insulin resistance. Longer duration of TAC and MI led to a decrease in purines, acylcarnitines, fatty acids and several lysolipid and sphingolipid species, but a marked increase in pyrimidines as well as ascorbate, heme and other indices of oxidative stress. Cardiac remodeling and contractile dysfunction in hypertrophied hearts were associated also with large increases in myocardial, but not plasma, levels of the polyamines putrescine and spermidine as well as the collagen breakdown product prolylhydroxyproline. Conclusions These findings reveal extensive metabolic remodeling common to both hypertrophic and failing hearts that are indicative of extensive extracellular matrix remodeling, insulin resistance and perturbations in amino acid, lipid and nucleotide metabolism.

Background Exercise promotes metabolic remodeling in the heart, which is associated with physiologic cardiac growth; however, it is not known whether or how physical activity-induced changes in cardiac metabolism cause myocardial remodeling. In this study, we tested whether exercise-mediated changes in cardiomyocyte glucose metabolism are important for physiologic cardiac growth. Methods We used radiometric, immunologic, metabolomic, and biochemical assays to measure changes in myocardial glucose metabolism in mice subjected to acute and chronic treadmill exercise. To assess the relevance of changes in glycolytic activity, we determined how cardiac-specific expression of mutant forms of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK2) affect cardiac structure, function, metabolism, and gene programs relevant to cardiac remodeling. Metabolomic and transcriptomic screenings were used to identify metabolic pathways and gene sets regulated by glycolytic activity in the heart. Results Exercise acutely decreased glucose utilization via glycolysis by modulating circulating substrates and reducing phosphofructokinase activity; however, upon exercise adaptation and recovery there was an increase in myocardial phosphofructokinase activity and glycolysis. Cardiac-specific expression of a kinase-deficient PFK2 transgene (GlycoLo mice) lowered glycolytic rate and regulated the expression of genes known to promote cardiac growth. Hearts of GlycoLo mice had larger myocytes, enhanced cardiac function, and higher capillary-to-myocyte ratios. Expression of phosphatase-deficient PFK2 in the heart (GlycoHi mice) increased glucose utilization and promoted a more pathological form of hypertrophy devoid of transcriptional activation of the physiologic cardiac growth program. Modulation of phosphofructokinase activity was sufficient to regulate the glucose-fatty acid cycle in the heart; however, metabolic inflexibility caused by invariantly low or high phosphofructokinase activity caused modest mitochondrial damage. Transcriptomic analyses showed that glycolysis regulates the expression of key genes involved in cardiac metabolism and remodeling. Conclusions Exercise-induced decreases in glycolytic activity stimulate physiologic cardiac remodeling, and metabolic flexibility is important for maintaining mitochondrial health in the heart.

Intermittent hypoxia (IH) during sleep, a critical feature of sleep apnea, induces significant neurobehavioral deficits in the rat. Cyclooxygenase (COX)-2 is induced during stressful conditions such as cerebral ischemia and could play an important role in IH-induced learning deficits. We therefore examined COX-1 and COX-2 genes and COX-2 protein expression and activity (prostaglandin E2 [PGE2] tissue concentration) in cortical regions of rat brain after exposure to either IH (10% O2 alternating with 21% O2 every 90 seconds) or sustained hypoxia (10% O2). In addition, the effect of selective COX-2 inhibition with NS-398 on IH-induced neurobehavioral deficits was assessed. IH was associated with increased COX-2 protein and gene expression from Day 1 to Day 14 of exposure. No changes were found in COX-1 gene expression after exposure to hypoxia. IH-induced COX-2 upregulation was associated with increased PGE2 tissue levels, neuronal apoptosis, and neurobehavioral deficits. Administration of NS-398 abolished IH-induced apoptosis and PGE2 increases without modifying COX-2 mRNA expression. Furthermore, NS-398 treatment attenuated IH-induced deficits in the acquisition and retention of a spatial task in the water maze. We conclude that IH induces upregulation and activation of COX-2 in rat cortex and that COX-2 may play a role in IH-mediated neurobehavioral deficits.

Objective To examine the cellular and molecular mechanisms underlying alcoholic cardiomyopathy. Background The mechanism for alcoholic cardiomyopathy remains largely unknown. Results Mice were fed alcohol or isocaloric control diet for 2 months. As compared with control, hearts from alcohol-fed mice exhibited increased apoptosis, along with significant nitrative damage, demonstrated by 3-nitrotyrosine (3-NT) abundance. Alcohol exposure to H9c2 cells induced apoptosis, accompanied by 3-NT accumulation and nicotinamide adenine dinucleotide phosphate oxidase (NOX) activation. Pre-incubation of H9c2 cells with urate (peroxynitrite scavenger), L-NAME (nitric oxide synthase inhibitor), MnTMPyP (SOD mimetic) and apocynin (NOX inhibitor) abrogated alcohol-induced apoptosis. Furthermore, alcohol exposure significantly increased the expression of angiotensin II (Ang II) and its type 1 receptor (AT1). A protein kinase C (PKC)-α/β1 inhibitor or PKC-β1 siRNA and an AT1 blocker prevented alcohol-induced activation of NOX, and AT1 blocker losartan significantly inhibited the expression of PKC-β1, indicating that alcohol-induced activation of NOX is mediated by PKC-β1 via AT1. To define the role of AT1-mediated PKC/NOX-derived superoxide generation in alcohol-induced cardiotoxicity, mice with knockout of AT1 gene (AT1-KO) and wide-type mice were simultaneously treated with alcohol for 2 months. Knockout AT1 gene completely prevented cardiac nitrative damage, cell death, remodeling and dysfunction. More importantly, pharmacological treatment of alcoholic mice with superoxide dismutase mimetic also significantly prevented cardiac nitrative damage, cell death and remodeling. Conclusions Alcohol-induced nitrative stress and apoptosis, which is mediated by Ang II interaction with AT1 and subsequent activation of a PKCβ1-dependent NOX pathway, is a causal factor in the development of alcoholic cardiomyopathy.

The CA1 and CA3 regions of the hippocampus markedly differ in their susceptibility to hypoxia in general, and more particularly to the intermittent hypoxia that characterizes sleep apnea. Proteomic approaches were used to identify proteins differentially expressed in the CA1 and CA3 regions of the rat hippocampus and to assess changes in protein expression following a 6-h exposure to intermittent hypoxia (IH). Ninetynine proteins were identified, and 15 were differentially expressed in the CA1 and the CA3 regions. Following IH, 32 proteins in the CA1 region and only 7 proteins in the more resistant CA3 area were up-regulated. Hypoxia-regulated proteins in the CA1 region included structural proteins, proteins related to apoptosis, primarily chaperone proteins, and proteins involved in cellular metabolic pathways. We conclude that IH-mediated CA1 injury results from complex interactions between pathways involving increased metabolism, induction of stress-induced proteins and apoptosis, and, ultimately, disruption of structural proteins and cell integrity. These findings provide initial insights into mechanisms underlying differences in susceptibility to hypoxia in neural tissue, and may allow for future delineation of interventional strategies aiming to enhance neuronal adaptation to IH. Keywords: apoptosis, intermittent hypoxia, neuronal vulnerability, obstructive sleep apnea, proteomics, rat hippocampus. Obstructive sleep apnea (OSA) is a condition characterized by repeated episodes of upper-airway obstruction during sleep, and affects 2-5% of the general population (National Heart and Blood Institute Working Group on Sleep Apnea 1996; Partinen and Telakivi 1992;Redline and Young 1993, Redline et al. 1994Redline and Strohl 1998). The major deleterious consequences of untreated OSA can be partitioned into two major groups, namely cardiovascular (Fletcher et al. 1992;Lavie et al. 1993;Fletcher 1995;Greenberg et al. 1999;Mooe et al. 2001) and neurocognitive morbidities (Kales et al. 1985;Roehrs et al. 1995;Gozal 1998). A major hallmark of OSA is the occurrence of intermittent hypoxia (IH) during sleep. We have recently established a rodent model whereby IH is associated with the typical neurocognitive deficits of OSA in the absence of sleep disturbances (Gozal et al. 2001). Indeed, IH slowed acquisition and impaired retention of a spatial reference task, but did not affect performance of non-spatial reference task as measured in the Morris water maze (Gozal et al. 2001). In addition, IH resulted in cellular changes and architectural disorganization in brain areas associated with neurocognitive function, such as the cortex and CA1 region of the hippocampus, but not the CA3 region of the hippocampal formation (Gozal et al. 2001). These findings are compatible with the concept of a slowly evolving, weak excitotoxicity process that may occur as a consequence of impaired cellular energy metabolism, free-radical production, and/or modifications in ion/receptor complexes (Albin and Greenamyre Received May 7, 2002;...