Influence of substrate on oxygen consumption of isolated perfused rat heart

Abstract

Techniques are described for the determination of substrate and O2 consumption by the rat Langendorff preparation beating at its intrinsic rhythm. The uptakes of substrate and O, were estimated in hearts perfused with a balanced salt solution containing glucose, lactate, pyruvate, acetoacetate (all 10 m[image]) or fatty acid (1 m[image], complexed to 1.5% defatted human albumin). Hearts fed glucose consumed approximately 300 pinoles of 02/g wet tissue per hr. This is considerably less than the amount taken up by hearts fed the other substrates mentioned (400-550 [mu]moles/g per hr.). The contribution of the exogenous substrate to O2 consumption (O2 extraction ratio) is also much smaller for glucose (27%) than for the other substrates (40-50%). Coronary flow and amplitude and frequency were also found to be substrate dependent in the experimental setup used.