Figure 3. Heart rate responses for dobutamine and epinephrine used alone, and their various combinations, in eight patients having aortocoronary bypass surgery who received dobutamine at doses of 0, 1.25, 2.5, and 5 [micro sign]g [middle dot] kg-1[middle dot] min-1, and epinephrine at doses of 0, 10, 20, and 40 ng [middle dot] kg-1[middle dot] min-1. See “Results” for a discussion of significant changes and Table 1for a summary of the drug administration protocol. Data points are slightly offset along the abscissa to eliminate overlap of the symbols in Figure 3and Figure 4.