Although caveolin-1 is not expressed in cardiomyocytes, this protein is assumed to act as a key regulator in the development of cardiomyopathy. In view of recent discordant findings we aimed to elucidate the cardiac phenotype of independently generated caveolin-1 knockout mice (cav-1 (-/-)) and to unveil causative mechanisms. Invasive hemodynamic measurements of cav-1 (/) show a severely reduced systolic and diastolic heart function. Additionally. genetic ablation of caveolin-1 leads to a striking biventricular hypertrophy and to a sustained eNOS-hyperactivation yielding increased systemic NO levels. Furthermore. a diminished ATP content and reduced levels of cyclic AMP in hearts of knockout animals were measured. Taken together. these results indicate that genetic disruption of cavcolin-1 is sufficient to induce a severe biventricular hypertrophy with signs of systolic and diastolic heart failure. Collectively, our findings suggest a causative role of a sustained nitrosative stress in the development of the pronounced cardiac impairment. (c) 2005 Elsevier Inc. All rights reserved.