Coronary pressure determines regional glucose uptake in the left ventricular wall of the heart

The effect of coronary and intraventricular pressures on the glucose uptake and its transmural distribution was studied in isolated, beating rat heart perfused using the Langendorff procedure. Left ventricular glucose uptake measured by the deoxyglucose method, and the effect of coronary (aortic) pressure was dissociated from intraventricular pressure development by draining the left ventricle. Left ventricular glucose uptake was 2.6 +/- 0.1 mumols/min per g protein (mean +/- S.E.M.) and 35 +/- 6% higher (P less than 0.001) in the subendocardium than in the subepicardium under control conditions (aortic pressure 80 cm H2O, non-drained). Elimination of the intraventricular pressure development caused no significant change in the total left ventricular glucose uptake or its transmural distribution. Increase in the aortic pressure to 150 cmH2O accelerated glucose uptake in non-drained and drained hearts by 57-75%. The increase in the glucose uptake was more pronounced in the subepicardial layer than in the subendocardial layer, so that the transmural gradient decreased by 27-32% (P less than 0.001) in non-drained and drained hearts. The results indicate that in Langendorff-perfused heart the effect of aortic pressure on the total glucose uptake and its transmural distribution across the left ventricular wall is not mediated through intraventricular pressure development, but through the coronary pressure.