Phosphocreatine and ATP concentrations increase during flow-stimulated metabolism in a non-contracting muscle

Mejsnar, J; Kushmerick, Martin J.; Williams, D.B.

doi:10.1007/bf01948004

Cited by 5 publications

(6 citation statements)

References 7 publications

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“…The data from this study confirm the stimulatory effect of perfusion flow rate on oxygen consumption in a muscle with open microcirculation, perfused and superfused in vitro (Chinet & Mejsnar, 1989;Mejsnar et al 1992;Stefl et al 1994). On a macroscopic scale the delivery of oxygen was sufficiently high to cover oxidative metabolism, even under a low perfusion rate, so that the availability of oxygen is not the cause of the flow dependency of the muscle oxygen consumption.…”

Section: Discussionsupporting

confidence: 82%

Energy Metabolism of Rat Skeletal Muscle Modulated by the Rate of Perfusion Flow

1999

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In order to advance our understanding of the phenomenon of flow-induced increases in the metabolism of the relaxed muscle, the metabolic rate of the isolated rat gracilis muscle was investigated at 28 degrees C in vitro. The muscle was perfused with cell-free Krebs-Henseleit bicarbonate buffer containing 5% bovine serum albumin and 5 mM glucose, saturated with a gas mixture of 95% O2 and 5% CO2 and simultaneously superfused with a medium saturated with with a low O2 gas mixture (1% O2, 5% CO2 and 94% N2). Two different perfusion flow rates (0.054 and 0.100 ml min-1) have been used. Their influence on oxygen consumption and lactate production has been measured. After a 100 min perfusion period, the muscle was freeze-clamped and analysed for ATP, phosphocreatine, creatine, lactate, pyruvate, inorganic phosphate and glycogen content. The energy state of the cell and the proportions of glycolytic and mitochondrial fluxes of ATP synthesis were evaluated. During perfusion at the low flow rate of 0.054 ml min-1, the oxygen uptake was 45 +/- 9 nmol min-1 (g wet wt)-1, accompanied by a dominance of anaerobic glycolytic synthesis of ATP over mitochondrial ATP synthesis, even though the total delivery of oxygen to muscle was three times higher than oxygen consumption. Increasing the perfusion flow rate to 0.100 ml min-1 increased the oxygen uptake to 120 +/- 6 nmol min-1 (g wet wt)-1, thus leading to a prevalence of mitochondrial ATP synthesis over glycolytic ATP synthesis. The inner stores of glycogen served as the main substrate of energy metabolism and the role of exogenous substrates in the flow-stimulated increase of oxygen uptake was negligible. The increase in perfusion rate also enhanced the energy state of the muscle fibres, which was expressed either as the creatine charge or as the value of the change of Gibbs free energy of ATP hydrolysis. Data indicate that the change of perfusion flow rate per se, apart from oxygen and exogenous substrate supply, elicits changes in the regulation of energy metabolism within non-contracting skeletal muscle under open microcirculation.

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Section: Discussionsupporting

confidence: 82%

Energy Metabolism of Rat Skeletal Muscle Modulated by the Rate of Perfusion Flow

1999

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“…Group 2: after 40 min recovery period with a perfusion flow rate of 0·054 ml min¢, the perfusion flow rate was increased to 0·100 ml min¢ for the next 60 min; n = 7. Controls: intact muscles of anaesthetized rats freezeclamped in situ; n = 10. discussion The data from this study confirm the stimulatory effect of perfusion flow rate on oxygen consumption in a muscle with open microcirculation, perfused and superfused in vitro (Chinet & Mejsnar, 1989;Mejsnar et al 1992;Stefl et al 1994). On a macroscopic scale the delivery of oxygen was sufficiently high to cover oxidative metabolism, even under a low perfusion rate, so that the availability of oxygen is not the cause of the flow dependency of the muscle oxygen consumption.…”

Section: Proportions Of Anaerobic and Aerobic Atp Synthesis Ratessupporting

confidence: 82%

“…The authors found that the energy fluxes measured by indirect and direct calorimetry differ, the former being higher in the range of perfusion rates from 50 to 150 ìl min¢ than the latter. This finding was further reinforced by the measurements of the increase in tissue levels of ATP and phosphocreatine (PCr) with 31 Pnuclear magnetic resonance spectroscopy (Mejsnar et al 1992) and by thermodynamic implications of the data (Mejsnar, 1991).…”

mentioning

confidence: 93%

Energy Metabolism of Rat Skeletal Muscle Modulated by the Rate of Perfusion Flow

Stefl

Mejsnar

Janovská

1999

Experimental Physiology

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summaryIn order to advance our understanding of the phenomenon of flow-induced increases in the metabolism of the relaxed muscle, the metabolic rate of the isolated rat gracilis muscle was investigated at 28°C in vitro. The muscle was perfused with cell-free Krebs-Henseleit bicarbonate buffer containing 5% bovine serum albumin and 5 mÒ glucose, saturated with a gas mixture of 95% Oµ and 5% COµ and simultaneously superfused with a medium saturated with a low Oµ gas mixture (1% Oµ, 5% COµ and 94% Nµ). Two different perfusion flow rates (0·054 and 0·100 ml min¢) have been used. Their influence on oxygen consumption and lactate production has been measured. After a 100 min perfusion period, the muscle was freeze-clamped and analysed for ATP, phosphocreatine, creatine, lactate, pyruvate, inorganic phosphate and glycogen content. The energy state of the cell and the proportions of glycolytic and mitochondrial fluxes of ATP synthesis were evaluated. During perfusion at the low flow rate of 0·054 ml min¢, the oxygen uptake was 45 ± 9 nmol min¢ (g wet wt)¢, accompanied by a dominance of anaerobic glycolytic synthesis of ATP over mitochondrial ATP synthesis, even though the total delivery of oxygen to muscle was three times higher than oxygen consumption. Increasing the perfusion flow rate to 0·100 ml min¢ increased the oxygen uptake to 120 ± 6 nmol min¢ (g wet wt)¢, thus leading to a prevalence of mitochondrial ATP synthesis over glycolytic ATP synthesis. The inner stores of glycogen served as the main substrate of energy metabolism and the role of exogenous substrates in the flow-stimulated increase of oxygen uptake was negligible. The increase in perfusion rate also enhanced the energy state of the muscle fibres, which was expressed either as the creatine charge or as the value of the change of Gibbs free energy of ATP hydrolysis. Data indicate that the change of perfusion flow rate per se, apart from oxygen and exogenous substrate supply, elicits changes in the regulation of energy metabolism within non-contracting skeletal muscle under open microcirculation.

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“…It would a tabolism in cold-exposed rats [32]. To further examine priori appear more reasonable to expect the opposite the sensitivity of creatine compounds and adenine nuresult based on the basal metabolic rates.…”

Section: Discussionmentioning

confidence: 98%

Creatine Phosphate as the Preferred Early Indicator of Ischemia in Muscular Tissues

Clark

Colquhoun

1996

Journal of Surgical Research

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Phosphocreatine and ATP concentrations increase during flow-stimulated metabolism in a non-contracting muscle

Cited by 5 publications

References 7 publications

Energy Metabolism of Rat Skeletal Muscle Modulated by the Rate of Perfusion Flow

Energy Metabolism of Rat Skeletal Muscle Modulated by the Rate of Perfusion Flow

Energy Metabolism of Rat Skeletal Muscle Modulated by the Rate of Perfusion Flow

Creatine Phosphate as the Preferred Early Indicator of Ischemia in Muscular Tissues

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