Introduction
β1-adrenergic antagonists have been recently used in septic patients to improve sepsis-induced immune, cardiovascular and coagulation dysfunction. But it is difficult and one is hesitant to use these drugs in septic shock patients who have already had hypotension because these drugs sometimes trigger excessive hypotension due to direct effects on heart function in addition to their β1 blocking effects. Since little is known about their acute direct effects on mammalian heart, we therefore evaluated the direct effects of esmolol, ultra-short-acting β-blockers, on cardiac performance and single cell-electrophysiology in guinea pig hearts, and compared these effects with those of landiolol.