Background: Pre- and Post-Conditioning have been shown to reduce significantly infarct sizes. However, the functionally recovery of the post-ischemic heart is not improved by these methods, irrespectively of the infarct size reduction. This study was aimed to investigate whether inotropic stimulation improves post-ischemic recovery differentially in pre- or post-conditioning. Methods: 96 hearts from normotensive rats were subdiveded into a non-ischemic control group (C) or exposed to 45 min global ischemia with pre-(IPC) or post-(IPoC) conditioning or withour (Isch). Hearts were reperfused for 120 min and LVDP, perfusion pressure (PP) and heart rate (HR) were monitored. Inotropic intervention by PTHrP (100 nM) and isoprenaline (10 nM) was performed 30 min after reperfusion. Results: IPC and IPoC significantly preserved the myocardial architecture that was desturbed in the Isch-grouop. PTHrP significantly reduced PP and increased HR in C and IPoC, but not in Isch and IPC. Similar, the PTHrP effect on LVDP was attenuated or restored. Isoprenaline reduced PP and increased HR and LVDP in all groups. Inhibition of PTHrP-receptors during ischemia preserved PTHrP responsiveness in the Isch-group. Conclusion: Ischemia desensitises PTHrP-receptors by endogeneously released PTHrP but post-conditioning restores the protective effects of this heart derived peptide.