Figure 11.

Mechanism of epinephrine–beta-blocker interaction. The cardiovascular influences of epinephrine are mediated via alpha, Beta-1, and Beta-2 receptors and are altered in patients medicated with nonselective beta blockers. These graphs distinguish typical cardiovascular responses after a 10-to 20-μg test dose of epinephrine in a normal versus a beta-blocked patient (see Table 4 for additional explanation). Note that the key underlying mechanism involves the influence of epinephrine on systemic vascular resistance and subsequent diastolic blood pressure (DBP).