Transmural gradient of glycogen metabolism in the normal rat left ventricle

Tata, Vincenzo De; Bergamini, Christian; Gori, Zina; Locci-Cubeddu, T; Bergamini, Ettore

doi:10.1007/bf00584699

Cited by 17 publications

(9 citation statements)

References 27 publications

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“…By this reasoning, the population of myocytes responsible for the majority of glycogen oxidation is different from the population which is responsible for glycolysis of exogenous glucose to lactate. This is consistent with the known transmural heterogeneity of the myocardium with respect to workload, blood flow (24), and enzymes pertaining to glycogen and glucose metabolism (25,26). The phenomenon of glycogen turnover, or simultaneous glycogen synthesis and degradation which we recently described in heart (3) could also be explained by cellular heterogeneity.…”

Section: Discussionsupporting

confidence: 88%

Preferential oxidation of glycogen in isolated working rat heart.

Goodwin¹,

Ahmad²,

Taegtmeyer³

1996

J. Clin. Invest.

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We tested the hypothesis that glycogen is preferentially oxidized in isolated working rat heart. This was accomplished by measuring the proportion of glycolytic flux (oxidation plus lactate production) specifically from glycogen which is metabolized to lactate, and comparing it to the same proportion determined concurrently from exogenous glucose during stimulation with epinephrine. After prelabeling of glycogen with either 14 C or 3 H, a dual isotope technique was used to simultaneously trace the disposition of glycogen and exogenous glucose between oxidative and non-oxidative pathways. Immediately after the addition of epinephrine (1 M), 40-50% of flux from glucose was directed towards lactate. Glycogen, however, did not contribute to lactate, being almost entirely oxidized. Further, glycogen utilization responded promptly to the abrupt increase in contractile performance with epinephrine, during the lag in stimulation of utilization of exogenous glucose, suggesting that glycogen serves as substrate reservoir to buffer rapid increases in demand. Preferential oxidation of glycogen may serve to ensure efficient generation of ATP from a limited supply of endogenous substrate, or as a mechanism to limit lactate accumulation during rapid glycogenolysis. ( J. Clin. Invest .

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Section: Discussionsupporting

confidence: 88%

Preferential oxidation of glycogen in isolated working rat heart.

Goodwin¹,

Ahmad²,

Taegtmeyer³

1996

J. Clin. Invest.

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“…This diversity results from a spectrum of fibers with different metabolic properties and different locations across the cardiac wall that may be especially suited to the local range of functional demands (10,14). Our results show that a similar picture emerges when enzyme activities of adenosine metabolism are investigated and there is evidence that this factor may also be related to function.…”

Section: Discussionsupporting

confidence: 67%

“…and killed by rapid injection of 1.0 ml cold 150 mM KCI. The arrested, fully relaxed hearts were removed and rinsed in ice-cold St. Thomas' cardioplegic solution (9) and a piece of the left and of the right ventricles were excised and frozen between two alumininm blocks at -30~ without any compression and cut into 100-~m-thick sections in a cryostat at -25 ~ as described (10). Four adjoining sections were combined and homogenized in a Potter Elvehjem apparatus (Thomas, Philadelphia, Pennsylvania, USA).…”

Section: Animalsmentioning

confidence: 99%

The regional distribution of adenosine-regulating enzymes in the left and right ventricle walls of control and hypertrophic heart

Tata¹,

Gini²,

Simonetti³

et al. 1989

Basic Res Cardiol

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The transmural distribution of the adenosine-generating enzyme 5'-nucleotidase (5'N) and of the adenosine-degrading enzymes adenosine deaminase (ADA), AMP deaminase (AMP-D) and adenosine kinase (Ado-K) were determined across the walls of left and right ventricles of control and hypertrophic rat hearts. The enzyme distribution across the left ventricle wall (but not across the right wall) of normal hearts was not uniform: 5'N activity shows its highest levels in the subepicardial and in the subendocardial regions, whereas all the other enzyme activities show their lowest levels. A similar pattern of transmural distribution was also detected in other mammalian species (ox and pig). In the experimental cardiac hypertrophy, caused by two different types of chronic cardiac overload, the levels and the profiles of transmural distribution of 5'N and ADA enzyme activities may significantly change across the rat left ventricle wall.

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“…Second, Goodwin et al (35) have recently demonstrated that the isolated working rat heart oxidizes glycogen rather than exogenous glucose during stimulation of glycogenolysis with epinephrine. This was attributed to transmural heterogeneity of the myocardium with respect to workload, blood flow (36), and glucose metabolizing enzymes (37,38). The same group has also described the phenomenon of glycogen turnover, i.e., simultaneous glycogen synthesis and breakdown in the heart (34).…”

Section: Discussionmentioning

confidence: 95%

Incorporation of [3-3H]Glucose and 2-[1-14C]Deoxyglucose Into Glycogen in Heart and Skeletal Muscle In Vivo: Implications for the Quantitation of Tissue Glucose Uptake

Virkamäki

Rissanen²,

Hämäläinen³

et al. 1997

Diabetes

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2-deoxyglucose has been widely used to quantitate tissue glucose uptake in vivo, assuming that 2-deoxyglucose is transported and phosphorylated but not further metabolized. We examined the validity of this assumption by infusing [3-3H]glucose and 2-[1-14C]deoxyglucose in a similar primed continuous fashion to chronically catheterized, freely moving rats during normoglycemic hyperinsulinemic conditions. The rates of 2-deoxyglucose uptake were determined from the accumulation of 2-[1-14C]deoxyglucose-6-phosphate and 2-[1-14C]deoxyglucose-6-phosphate combined with the rate of the incorporation of 2-[1-14C]deoxyglucose into glycogen in rectus abdominis muscle and the heart. When the rates of glycogen synthesis during the 2-h hyperinsulinemic period from the two tracers were compared in rectus abdominis muscle, the rate of glycogen synthesis was twofold higher when measured with [3-3H]glucose (337 +/- 14 micromol x kg(-1) x min(-1)) than when measured with 2-[1-14C]deoxyglucose (166 +/- 10 micromol x kg(-1) x min(-1), P < 0.001). In the heart, the rate of glycogen synthesis was twofold higher when measured with 2-[1-14C]deoxyglucose (141 +/- 20 micromol x kg(-1) x min(-1)) than when measured with [3-3H]glucose (72 +/- 15 micromol x kg(-1) x min(-1), P < 0.001). The rate of 2-deoxyglucose uptake was 29% underestimated in rectus abdominis muscle, when counts found in glycogen were not included in glucose uptake calculations (398 +/- 25 vs. 564 +/- 25 micromol x kg(-1) x min(-1), P < 0.001). In the heart, glucose uptake was underestimated by 7% if glycogen counts were not taken into account (1,786 +/- 278 vs. 1,926 +/- 291 micromol x kg(-1) dry x min(-1), P < 0.05). The fraction of [3-3H]glucose incorporated into glycogen of total glucose metabolism (calculated from 2-deoxyglucose conversion to 2-deoxyglucose-6-phosphate and glycogen) was 0.6 (337/564) in rectus abdominis muscle and 0.037 (72/1,926) in the heart. We conclude that 2-deoxyglucose is incorporated into glycogen in the heart and in skeletal muscle in vivo under normoglycemic hyperinsulinemic conditions in the rat. Failure to consider the incorporation of 2-deoxyglucose into glycogen will underestimate the rate of tissue glucose uptake. To avoid such problems, the amount of 2-deoxyglucose incorporated into glycogen should be quantitated in subsequent studies.

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Transmural gradient of glycogen metabolism in the normal rat left ventricle

Cited by 17 publications

References 27 publications

Preferential oxidation of glycogen in isolated working rat heart.

Preferential oxidation of glycogen in isolated working rat heart.

The regional distribution of adenosine-regulating enzymes in the left and right ventricle walls of control and hypertrophic heart

Incorporation of [3-3H]Glucose and 2-[1-14C]Deoxyglucose Into Glycogen in Heart and Skeletal Muscle In Vivo: Implications for the Quantitation of Tissue Glucose Uptake

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