AJP - Heart and Circulatory Physiology, Vol 253, Issue 1 31-H40, Copyright © 1987 by American Physiological Society
Relation between oxygen consumption and pressure-volume area of in situ dog heart
T. Nozawa, Y. Yasumura, S. Futaki, N. Tanaka, Y. Igarashi, Y. Goto and H. Suga
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.
