Regional glucose consumption and oxygen supply in the isolated perfused working rat heart

Using 2-Deoxyglucose as a tracer, regional myocardial metabolic rate of glucose (MMR GL) has been determined in an isolated perfused working heart preparation. Under control conditions (n = 8) mean glucose consumption of the left ventricular wall amounted to 1.17 +/- 0.24 mumol X g-1 X min-1, which was about twice that of the right ventricular wall. There was an inhomogeneous distribution of MMR GL in the left ventricular wall with the endocardial rates exceeding the epicardial ones by about 20%. Isoprenaline (1.25 micrograms X L, n = 9) induced an increase in heart rate and a decrease in cardiac output. Under these conditions mean glucose consumption increased by about 20%, and a redistribution of MMR GL was observed in the left ventricular wall. As, in the preparation used, only glucose was offered as an exogeneous substrate, this redistribution should reflect a similar redistribution of myocardial energy metabolism and, therefore, muscular tension developed in the different layers of the ventricular wall.