The conundrum of the effect of β-blockade on myocardial oxygen consumption

Abstract The effect of propranolol on myocardial oxygen consumption was studied in in situ canine hearts. In 12 afterload independent isovolumic hearts propranolol increased M V O 2 an average of 19 ± 3% ( P P V O 2 is indexed for heart rate, heart weight, and stroke work. Therefore, propranolol does not decrease M V O 2 for individual contractions and does not affect the energy requirements for basal metabolism, excitation-contraction coupling, and heat generation, in contrast to results obtained with β agonists.