Does exercise affect cardiac output, left coronary flow, and myocardial metabolism in unanesthetized dogs?
In unanesthetized dogs, moderately severe exercise increases cardiac output and coronary flow by 350-400%, primarily driven by increased heart rate rather than stroke volume.
Cardiac output, left coronary artery flow, central aortic blood pressure and myocardial metabolism have been studied in the intact unanesthetized dog during exercise. Cardiac output and left coronary artery flow increase 350 to 400% during moderately severe exercise. The primary mechanical determinant of this increase appears to be cardio-acceleration; the stroke volume and stroke coronary flow contribution is relatively mild. Myocardial oxygen usage increases 300% or more with only a small elevation of the percentage of extraction of oxygen. The large increase of coronary flow in the dog and the significant elevation in hematocrit supply the extra oxygen.
KHOURI et al. (1965) studied this question.