Effect of pressure development on oxygen consumption

NEELY, ,J. R., H. LIEBERMEISTER. E.,J. BATTERSBY, AND H. E. MORGAN. fi;fect of pressure development on oxygen consumption by isolcrted rot heart. Am. J. Physiol. 2 I 2 (4) : 804-814. I g67.-The isolated perfused rat heart has been modified to allow metabolic studies over a range of heart work and pressure development. When the left atria1 filling pressure was increased from o to 20 cm H20, cardiac output increased fivefold and systolic aortic pressure rose from 60 to 120 mm Hg. The mechanical performance and oxygen consumption were stable for over 3 hr when the heart was perfused with Krebs-Henseleit bicarbonate bufl’er containing only glucose. Variation in mechanical performance and oxygen 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 oxygen consumption involved in generation of mechanical energy. Oxygen supply to the tissue appeared to be adequate. Oxygen consumption increased from an average of I .44 to 2 .g5 mmoles/g per hr as atria1 pressure was increased from o to 20 cm Hz0 when hearts were perfused with buffer containing either no nutrients, 5 mM glucose, 5 mM acetoacetate, or 5 mM acetate.