Methods for the Preparation of an Excised, Cross-Circulated Rat Heart

The Emax-Pressure-Volume Area (PVA)-VO₂ framework proposed by Dr. Suga for canine hearts has dramatically advanced the field of cardiac mechanical work and energetics, i.e., mechanoenergetics. He and his collaborators investigated mechanoenergetics in the left ventricle (LV) of excised, cross-circulated canine heart preparations. We instituted the excised cross-circulated rat whole heart preparations and found a curvilinear end-systolic pressure-volume relation (ESPVR) in the rat LV, in contrast to the linear ESPVR in canine, rabbit, and human LVs. Although Emax, the slope of the linear ESPVR, could be used as an index of LV contractility, it was not applicable for evaluating LV contractility in the rat LV. Thus, we proposed a new index of contractility, equivalent Emax (eEmax) in the rat LV. We also found a linear VO₂-PVA relationship in the rat LV. Here, we introduce the methods for the preparation of excised, cross-circulated rat whole hearts and the eEmax-PVA-VO₂ framework in the rat LV. Using this method, we can obtain accurate LV volume and myocardial O₂ consumption in real time for estimating cardiac mechanoenergetics, which is very challenging in in vivo experiments.