The applicability of the 2-deoxyglucose tracer method to the study of the tranamural distribution of glucose uptake in the left ventricle of the isolated, Langendorff-perfused rat heart was validated for the myocardium. The total 2-deoxy[*H]glucose trapped in the myocardium was proportional to the glucose uptake which was varied by the mechanical work load and availability of other oxidizable substrates. When the mechanical work of the heart was eliminated by K*-induced arrest, the glucose

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... e of 2.0 junol/min per g protein was evenly distributed across the left ventricular wall. In the beating heart, glucose uptake averaged 4.7 mol/min per g protein, and was about 40% higher in the subendocardial layer than in the eubepicardium {P < 0.001). Measurement of the transmural distribution of coronary flow by the microsphere method indicated that there were no areas of underperfusion in the left ventricle. The transmural gradient in glucose uptake probably is caused by uneven distribution of the mechanical work load. Circ Res 49: 62-69,1981 From the the transmural distribution of glucose uptake in the left ventricular wall on the basis of deoxyglucose trapping in the various layers of the myocardium. A transmural gradient of glucose uptake could be demonstrated in the beating heart. Methods Reagents 2-Deoxy-D-[ 3 H]glucose and D-[3-3 H]glucose were obtained from the Radiochemical Centre and nonradioactive 2-deoxy-D-glucose from Sigma Chemical Co. 14l Ce-labeled microspheres with a diameter of 14.7 + 1.1 /un (mean ± SD) were obtained from New England Nuclear, and standard reagents from E. Merck, A.G. Animals Male Sprague-Dawley rats weighing 270-330 g from the Department's own stocks were used. They were fed ad libitum on pelleted standard rodent chow (Hankkija Ltd.). Apparatus The perfusion apparatus was constructed essentially as described by Chain et al. (1969) . The perfusion fluid reservoirs connecting glass tubes and heart compartment were thermostated at 37°C. Rapid changes in the perfusion medium were achieved by means of suitable three-way stopcocks. A multibulb oxygenator was used for recirculation perfusion. Perfusion The rats were anesthetized with ether and injected with 500 IU heparin intravenously before by guest on August 15, 2017 http://circres.ahajournals.org/ Downloaded from 1.24 ±0.15 (6) Results are expressed BE mean ± SEM for the number of heart* given in parentheses. • Measured by using [3-°H]glueose, as described in the Methods section. f Glycolysis plus glycogenesia t Value at the end of the Last (wash-out) phase of the perfusion. by guest on August 15, 2017 http://circres.ahajournals.org/ Downloaded from isolated perfused rat heart, studied by regional deoxyglucose trapping. Effect of mechanical work load on the transmural distribution of glucose uptake in the Print ISSN: 0009-7330. Online