Exercise Preconditioning Preserves Cardiac Function and Enhances Cardiac Recovery Following Dobutamine Stimulation in Doxorubicin-Treated Rat Hearts

Exercise preconditioning has been shown to protect against DOX-induced cardiac dysfunction when hearts are maintained under resting conditions. However, it is unclear whether this exercise-induced protective effect is maintained when the heart is challenged with the β1-adrenergic receptor agonist dobutamine (DOB), which mimics acute exercise stress. Fischer 344 rats were randomly assigned to sedentary (SED) or voluntary wheel running (WR) groups for 10 weeks. At week 11, rats were treated with either 15 mg/kg DOX or saline (SAL). Five days later, ex vivo cardiac function was assessed using an isolating working heart model at baseline, during the infusion of 7.5 μg/kg/min DOB, and during recovery. DOB infusion significantly increased left ventricular developed pressure (LVDP), maximal (dP/dtmax) and minimal (dP/dtmin) rate of left ventricular pressure development, and heart rate in all groups (p