Effect of pressure development on oxygen consumption by isolated rat heart

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Abstract
The isolated perfused rat heart has been modified to allow metabolic studies over a range of heart work and pressure development. When the left atrial filling pressure was increased from 0 to 20 cm H2O, cardiac output increase 5-fold and dystolic aortic pressure rose from 60 to 120 mm Hg. The mechanical performance and O2 consumption were stable for over 3 hr. when the heart was perfused with Krebs-Henseleit bicarbonate buffer containing only glucose. Variation in mechanical performance and O2 consumption with hearts of various sizes has been noted, indicating that meaningful comparisons of performance must utilize hearts of similar size. Pressure development, as estimated from pressure-time integrals/correlated well with the portion of O2 consumption involved in generation of mechanical energy. Oxygen supply to the tissue appeared to be adequate. Oxygen consumption increased from an average of 1.44 to 2.95 mm/g per hr. as atrial pressure was increased from 0 to 20 cm H2O when hearts were perfused with buffer containing either no nutrients, 5 m[image] glucose, 5 m[image] aceto-acetate, or 5 m[image] acetate.