Effects of heart work and insulin on glycogen metabolism in the perfused rat heart

Das, Ishita

doi:10.1152/ajplegacy.1973.224.1.7

Cited by 14 publications

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“…Similarly, post-prandial elevations in circulating factors such as insulin are anticipated to promote glucose uptake and utilization by the heart, resulting in increased rates of glycolysis and glucose oxidation during the awake period (relative to the sleep phase), which persist in the ex vivo setting [28, 38]. A dichotomy exists for glycogen turnover, wherein increased cardiac work promotes glycogenolysis, while insulin stimulates glycogen synthesis [36, 39, 40]. However, it has been reported that in the heart net glycogen synthesis occurs during the active period (when cardiac work is increased), while net glycogenolysis occurs during the sleep phase [38].…”

Section: Time-of-day-dependent Changes In Myocardial Metabolismmentioning

confidence: 99%

Regulation of myocardial metabolism by the cardiomyocyte circadian clock

Chatham

Young

2013

Journal of Molecular and Cellular Cardiology

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On a daily basis, the heart is subjected to dramatic fluctuations in energetic demand and neurohumoral influences, many of which occur in a temporally predictable manner. In order to preserve cardiac performance, the heart must therefore maintain metabolic flexibility, even within the confines of a single day. Recent studies have established mechanistic links between time-of-day-dependent oscillations in myocardial metabolism and the cardiomyocyte circadian clock. More specifically, evidence suggests that this cell autonomous molecular mechanism regulates myocardial glucose uptake, flux through both glycolysis and the hexosamine biosynthetic pathway, and pyruvate oxidation, as well as glycogen, triglyceride, and protein turnover. These observations have led to the hypothesis that the cardiomyocyte circadian clock confers the selective advantage of anticipation of increased energetic demand during the awake period. Here, we review the accumulative evidence in support of this hypothesis thus far, and discuss the possibility that attenuation of these metabolic rhythms, through disruption of the cardiomyocyte circadian clock, contributes towards the etiology of cardiac dysfunction in various disease states.

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Section: Time-of-day-dependent Changes In Myocardial Metabolismmentioning

confidence: 99%

Regulation of myocardial metabolism by the cardiomyocyte circadian clock

Chatham

Young

2013

Journal of Molecular and Cellular Cardiology

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“…However, in our experiments, hearts were equilibrated with [3~]glucose and insulin for =50 min before inducing ischemia. Thus, a sufficient time was allowed for incorporation of labeled glucose into glycogen and for the perfusate glucose radioactivity to equilibrate with that of the endogenous glucose pool (34,35). This issue, however, deserves additional investigation.…”

Section: Discussionmentioning

confidence: 99%

Mechanical and Metabolic Characterization of Ischemic Contracture in the Neonatal Pig Heart

et al. 1995

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Isolated, paced, isovolumetrically beating piglet hearts ( n = 37) underwent retrograde aortic perfusion with a crystalloid solution during three periods: 1) baseline (coronary perfusion pressure 60 mm Hg), 2) ischemia (coronary flow 10% of baseline for -80 min), and 3) reperfusion (perfusion pressure returned to baseline). In one group of hearts, glycolysis (using "H,o formation from [3H]glucose) was assessed. During baseline, peak systolic pressure (PSP) was 101.1 i 5.0 mm Hg, end diastolic pressure (EDP) 4.4 z 0.5 mm Hg, glycolysis 970.5 -C 65.3 nmol/min/g,,,, and myocardial glycogen 234.8 2 12.0 pmoll g,,,. During ischemia, PSI' decreased to 23.3 t 2.7 mm Hg, BDP increased to 12.3 2 0.7 mm Hg, myocardial glycogen decreased to 181.5 2 30.3 pmol/g,,,, and lactate (-154 pmoll g,,,) and glycerol (-930 nmol/g,,,) were released. Myocardial contracture correlated with a decrease in lactate release. Glycolysis decreased to -400 nmol/min/g,,, and remained stable, accounting for =SO% of the lactate producetl. During reperfusion, PSP recovered to 79.8 2 3.5 mm llg, EDP 6.6 2 1.7 mm Hg, and glycolysis 1103.9 + 81 nmol/rnin/g,,,. In a second group of hearts, with similar mechanical responses, giucose oxidation (using "CO, formation from ['4C]glucose) was evaluated. During baseline, glucose oxidation was 165.4 -t 15.9 nmol/min/g,,, and correlated closely (r = 0.957) with rnechanical activity. With ischemia, glucose oxidation decreased to =17Myocardial contracture represents a state of decreased diastolic compliance of the ventricle secondary to a depletion of high energy stores in the region of the contractile apparatus (1).With ischemia, contracture occurs as a consequence of myocardial underperfusion, which results in inadequate substrate delivery and impaired ATP production. Insufficient ATP leads to a progressive increase in the number of myocin-actin complexes that are unable to dissociate and to derangements in resting cytosolic calcium levels (2). (3,4). Little is known about myocardial contracture in the setting of low-flow ischemia, where hearts are beating, and there is washout of metabolites. Additionally, the modalities of energy production and utilization associated with contracture are poorly understood, yet these processes ultimately determine myocardial viability. An understanding of these processes in neonatal hearts has significant clinical ramifications, because contracture is thought to represent a precursor to an irreversible myocardial injury (5).The objectives of the present investigation were to study myocardial contracture in isolated, isovolumetrically beating, neonatal pig hearts subjected to normothermic, low-flow isch-

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Cardiac Glycogen Metabolism in Diabetes

Laughlin¹

1996

The Heart in Diabetes

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Effects of heart work and insulin on glycogen metabolism in the perfused rat heart

Cited by 14 publications

References 0 publications

Regulation of myocardial metabolism by the cardiomyocyte circadian clock

Regulation of myocardial metabolism by the cardiomyocyte circadian clock

Mechanical and Metabolic Characterization of Ischemic Contracture in the Neonatal Pig Heart

Cardiac Glycogen Metabolism in Diabetes

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