Characterization of the protective effects of cardiotrophin-1 against non-ischemic death stimuli in adult cardiomyocytes

The aim of this study was to investigate the cytoprotective effects of CT-1 against non-ischemic death stimuli in adult cardiomyocytes. Primary cultures of cardiomyocytes isolated from adult rats were stimulated with either angiotensin II (Ang II) or H2O2 in the presence or absence of CT-1. Cell death was determined by trypan blue exclusion, cell viability by MTT assay and apoptosis by TUNEL-Annexin-V staining. Intracellular pathways were analyzed by the employment of chemical inhibitors and by the assessment of signalling intermediates phosphorylation by Western blot analysis. CT-1 reduced (p < 0.01) total cell death and apoptosis induced by either Ang II or H2O2, and increased (p < 0.01) cell viability in cardiomyocytes exposed to these stimuli. These effects of CT-1 were abolished in the presence of antibodies specific for gp130 or LIFR and did not require RNA or protein synthesis. Both Wortmannin and PD98059 abolished protective effects of CT-1 against H2O2, whereas only Wortmannin inhibited protection against Ang II. In both cases, Akt kinase activation and Bad phosphorylation were observed. These findings suggest that CT-1 protects adult cardiomyocytes against Ang II- and oxidative stress-induced cell death, via gp130/LIFR and by means of the PI3K/Akt and the p42/44 MAPK intracellular cascades.