Positive effects of cardiac progenitor cells (CPC) on heart function and remodelling processes are manifold. Paracrine mechanisms are commonly discussed but still very speculative. The present study tries to answer the question of whether CPC insert different effects in addiction of the underlying cardiovascular diseases of the donor. Therefore CPC from normotensive Wistar-rats (Wis) and hypertensive SHR (SHR) were generated (Messina et al.). Conditioned media of these CPC were either tested on isolated myocytes of Wis or SHR. Contractile function of Wis and SHR myocytes were examined after 24h of incubation with the respective media. Additionally hypertrophy- and apoptosis-associated, and Ca²⁺-regulating proteins of these cellular cultures were examined by western blotting. 18 released cytokines were examined. Conditioned media of CPC isolated from SHR ameliorated contractile function of myocytes isolated from SHR (+33% dl/l) as well as myocytes isolated from Wis (+21% dl/l). The positive effect on contractile function of CPC isolated from Wis was less concisely in myocytes isolated from Wis (+19% dl/l) and there was almost no positive effect on contractile function measured in myocytes isolated from SHR. In myocytes isolated from Wis incubated with conditioned media of CPC generated from SHR the following proteins were regulated: the anti-apoptotic protein bcl-2 was up-regulated, bax remained stable, and the TGFbeta expression and the SERCA/NCX ratio increased. Hoe staining showed an apoptosis rate of 16% in these cellular cultures incubated with conditioned medium and of 23% in cells incubated with the respective pure media. The following differences concerning the released cytokines between CPC isolated from SHR and from Wis occurs: CNTF, Lix, Leptin, betaNGF and MIP3a were considerably less released from CPC isolated from SHR. The only cytokine that was conspicuously increased released was IL-6. The derivation and underlying cardiovascular diseases are important variables for the magnitude of the examined positive paracrine mechanisms of CPC. If this is true for the above mentioned released cytokines needs to be clarified in onward studies.