Effect of adrenaline on myocardial oxygen consumption during selective and non-selective beta-adrenoceptor blockade comparison of atenolol and pindolol.

The effect of adrenaline on myocardial oxygen consumption (MVO2) during selective and non-selective beta-adrenoceptor blockade was examined in 26 patients with angina pectoris. Cardiac venous flow was measured by thermodilution and blood was sampled for metabolic studies. Thirteen patients were given atenolol 62.5 micrograms/kg i.v. and the other 13 patients pindolol 7.5 micrograms/kg i.v. Measurements were repeated before and during infusion of adrenaline 0.1 microgram/kg/min. Compared to the control situation, adrenaline increased MVO2 more in atenolol-treated (39%) than in pindolol-treated patients (11%). This was partly due to augmented external cardiac work. Arterial FFA was considerably increased in the atenolol group (105%), but was unchanged in the pindolol group, suggesting an additional metabolic mechanism. Thus, adrenaline stimulation, which is comparable to that found in acute myocardial infarction, increases MVO2 more during selective than non-selective beta-blockade.