RESUMO
The current use of the rat working heart for in vitro assessment of myocardial functions prompted us to modify the rabbit Langendorff heart preparation, which is frequently used in the research field of pharmacology, to the working-heart preparation. The left atrium of the rabbit Langendorff heart was cannulated; oxygenated Krebs--Henseleit solution was perfused into the atrium at an arbitrary hydrostatic pressure. At a pressure of 20 cm H2O the rabbit heart pumped the solution against a hydrostatic pressure of 100 cm H2O and gave the following values: aortic flow (66.4 +/- 2.9 ml/min), systolic aortic pressure (78.4 +/- 3.1 mm Hg), coronary flow (39.0 +/- 2.7 ml/min), and heart rate (151 +/- 9.5 beats/min). Recovery of these functions was observed after an ischemic heart arrest was induced by an infusion of cold Young's solution. The protective effect of GIK, a well-known cardioplegic solution, was assessed using this working heart system.