Regional glucose uptake and protein synthesis in isolated perfused rat hearts immediately after training and later

Kainulainen, Heikki; Komulainen, Jyrki; Takala, Timo; Vihko, V.

doi:10.1007/bf01907048

Cited by 8 publications

(11 citation statements)

References 38 publications

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“…In this, as in our previous studies (18,20), the uptake gradient of male rats vanished after training. Since the transmural distribution of glucose uptake probably reflects the distribution of the mechanical work load (see, e.g., (53)), this redistribution of the glucose utilization may reflect a corresponding redistribution of the left ventricular work load and may influence the distribution of the oxygen consumption/perfusion ratio (20).…”

Section: Regional Myocardial Glucose Uptakesupporting

confidence: 52%

“…Right ventricular glucose uptake was elevated after training, an observation not made in our previous studies. We have discussed the possible physiological significance of changed use of glucose in our recent papers (18,20,53).…”

Section: Regional Myocardial Glucose Uptakementioning

confidence: 97%

“…It is worth noting that swimming exercise causes a growth of the atria in both sexes. In our earlier papers, we have reported increases in atrial weights in male rats after long-term swimming training, but not after longterm running training (18,20).…”

Section: E[iectiveness Of Trainingmentioning

confidence: 98%

“…In previous studies we found that endurance training increases subepicardial glucose uptake in the isolated perfused hearts of male rats (18,20). We have proposed that the disappearance of the transmural gradient in glucose uptake reflects a redistribution of the myocardial work load as an adaptation of the heart to chronic exercise (18,53).…”

Section: Introductionmentioning

confidence: 97%

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Effect of chronic exercise on glucose uptake and activities of glycolytic enzymes measured regionally in rat heart

et al. 1989

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Regional glucose uptake in perfused hearts, and the activities of several glycolytic enzymes contributing to the glucose metabolism in perfused and nonperfused hearts were studied in male and female rats after 8-9 weeks of swimming training. The left ventricular glucose uptake showed a transmural gradient in the sedentary animals, the subendocardial uptake being 30% and 12% higher than that of the subepicardial layer in the males and females, respectively. Swimming exercise abolished the left ventricular glucose uptake gradient in male rats, and in female rats an opposite gradient was found, the subepicardial uptake being 23% higher than the subendocardial uptake. The activities of phosphofructokinase and 3-phosphoglyceraldehyde dehydrogenase also showed transmural gradients in the left ventricles. Training did not abolish these gradients. Training-induced changes in the activities of phosphofructokinase, 3-phosphoglyceraldehyde dehydrogenase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, citrate synthase, and malate dehydrogenase were found in certain sites of the myocardium. Perfusion of isolated hearts for 50 min with insulin-containing Krebs-Ringer buffer especially affected the activities of phosphofructokinase, lactate dehydrogenase, and citrate synthase, increasing these activities in the left ventricles and decreasing them in the atria. These results indicate that there are regional differences between male and female rats in the cardiac glucose uptake rate after swimming training.

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Section: Regional Myocardial Glucose Uptakesupporting

confidence: 52%

Section: Regional Myocardial Glucose Uptakementioning

confidence: 97%

Section: E[iectiveness Of Trainingmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 97%

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Effect of chronic exercise on glucose uptake and activities of glycolytic enzymes measured regionally in rat heart

et al. 1989

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“…Second, different exercise training may alter the result of GLUT4 protein expression. It has been shown that treadmill training cannot increase glucose uptake in cardiac muscles [19], but swimming resulted in a significant increase of glucose uptake [20]. Third, Hall et al provided no food to the exercised rats during postexercise recovery, whereas we fed glucose to all the rats following exercise.…”

Section: Discussionmentioning

confidence: 94%

Effect of Systemic Hypoxia on GLUT4 Protein Expression in Exercised Rat Heart

Chou

Chiu²,

Cho³

et al. 2004

JJP

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severe hypoxia can protect cardiac muscles from damage [4,5]. These previous studies suggest the importance of carbohydrate substrate in maintaining normal cardiac function under stress conditions that lower arterial PO 2 .Recently, altitude exercise training in "living hightraining low" fashion has been proposed to improve endurance performance in athletes [6]. The adaptive response of the cardiac muscles associated with glycogen storage under a hypoxia-training regimen has never been investigated. Previous study has shown that exercise, hypoxia, and myocardial ischemia (the acute conditions that reduce arterial PO 2 ) dramatically increase the rate of glucose transport, and this Japanese Journal of Physiology Vol. 54, No. 4, 2004 357 During exercise or hypoxia, carbohydrates become increasingly important as energy metabolism becomes more anaerobic. Under normal conditions, the working heart produces a constant and abundant supply of ATP, mainly relying on fat oxidation [1]. But when the rate of oxygen demand exceeds oxygen supply in the tissue, the ratio of energy reliance on fat will be forced to reduce. In this situation, carbohydrate substrate becomes crucial for sustaining normal tissue function. This is particularly evident in cardiac muscles because hypoxic stress can lead to a significant decrease in glycogen content of the tissue [2,3]. In this respect, it has been shown that interventions that enhance carbohydrate metabolism during Abstract: Altitude training is a common method used to enhance endurance performance in athletes. We have examined the interactive effect of exercise training and chronic hypoxic on glycogen storage and GLUT4 protein expression in cardiac muscles. Thirty-two male SpragueDawley rats were weight balanced and assigned to one of the following four groups: control, exercise, hypoxia, and hypoxia-exercise. Rats with hypoxic treatment (breathing 14% O 2 for 12 hr/d) were exposed under normobaric conditions. The training protocol consisted of swimming for two 3-hr periods per day for 4 weeks. Glycogen content, GLUT4 protein, and mRNA of all rats were determined 16 hr after treatments. Four-week exercise training without hypoxia significantly elevated myocardial glycogen level by 45%. The chronic hypoxic-exercise training elevated the myocardial glycogen level by 67% above control level, significantly greater than the exercise group. Chronic hypoxia, exercise training, and hypoxia-exercise training significantly elevated GLUT4 protein by 40-70% in cardiac muscles. Chronic hypoxia significantly elevates the GLUT1 protein level independent of exercise training.The new finding in this study was that GLUT4 gene expression in cardiac muscle can be stimulated by exercise training with hypoxia treatments. This molecular adaptation appears to be associated with the observed increase in glycogen storage of the muscle.

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Effects of training and anabolic steroids on collagen synthesis in dog heart

Takala

Rämö

Kiviluoma

et al. 1991

Europ. J. Appl. Physiol.

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The effects of endurance training and anabolic steroid (Methandienone 1.5 mg.kg-1 p. o. daily) and their combination on regional collagen biosynthesis and concentration in the hearts of male beagle dogs were studied by measuring prolyl 4-hydroxylase (PH) activity and hydroxyproline (HYP) concentration. The PH (P less than 0.05) and HYP (P less than 0.05) were both greater in the subendocardinal layer than in the subepicardium (EPI) of the left ventricular wall in controls, whereas opposite gradients (P less than 0.05) were observed in the right ventricle. Endurance exercise caused an increase of PH activity in EPI of the left ventricular wall (P less than 0.01). The HYP concentration increased in both layers of the right ventricle in the exercise plus steroid group (P less than 0.05). The results suggest that transmural differences exist in the rate of collagen synthesis and concentration in canine cardiac ventricles and that endurance exercise may accelerate collagen synthesis in EPI of the left ventricle and the combination of exercise and anabolic steroid causes an increase in collagen concentration in the right ventricular wall.

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Regional glucose uptake and protein synthesis in isolated perfused rat hearts immediately after training and later

Cited by 8 publications

References 38 publications

Effect of chronic exercise on glucose uptake and activities of glycolytic enzymes measured regionally in rat heart

Effect of chronic exercise on glucose uptake and activities of glycolytic enzymes measured regionally in rat heart

Effect of Systemic Hypoxia on GLUT4 Protein Expression in Exercised Rat Heart

Effects of training and anabolic steroids on collagen synthesis in dog heart

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