Relation between oxygen consumption and pressure-volume area of in situ dog heart.
We studied the relation between O2 consumption (VO2) and the systolic pressure-volume area (PVA) in the left ventricle of open-chest dogs. PVA and the slope (Emax) of the end-systolic pressure-volume line were determined by an abrupt occlusion of the ascending aorta. VO2 linearly correlated with PVA in control contractile state, where Emax was 15.8 +/- 4.4 (SD) mmHg/ml with intact reflexes and 11.5 +/- 1.2 mmHg/ml with blocked reflexes. Emax and the VO2 axis intercept of the VO2-PVA line were greater in the in situ heart than in the excised cross-circulated dog heart in our previous study. Enhancement of contractile state by dobutamine increased Emax by 60-80% and shifted the VO2-PVA line upward, increasing the VO2 axis intercept by 38% with intact reflexes and by 79% with blocked reflexes. The slope had a tendency to increase with dobutamine, but the increase was statistically insignificant. We conclude that PVA and Emax obtained by the aortic-occlusion method can account for changes in VO2 with changes in loading conditions and contractility in an in situ dog heart.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001810:Blood Volume / Q000187:drug effects; D004280:Dobutamine / Q000494:pharmacology; D004285:Dogs; D006321:Heart / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D012044:Regression Analysis
D004280:Dobutamine