Figure 7: (a) Representative Frank-Starling relationship from one animal at baseline (Base) and after treatment with dobutamine (DBT). (b) Comprehensive group data from all animals illustrating a significant leftward shift in the Frank-Starling relationship (mixed model, treatment main effect adjusted for EDV covariance, ). There was no significant interaction or change in slope of the Frank-Starling relationship between treatments (see table inset in (b)), therefore, parallelism was assumed. The y-intercept and marginal mean difference were both significantly increased following the dobutamine treatment (* ; table inset (b)). The dobutamine challenge resulted in a ~15% increase in stroke volume (SV) for a given end diastolic volume (EDV) in vivo. This increase in ventricular function was similar in magnitude to that observed in our myocyte preparations (~10%), illustrating the coherence of our whole heart and cardiac myocyte functional data.