Arterial pulmonary hypertension is a rare disease, with little knowledge regarding its etiology, and high mortality. Development of right and later on also left ventricular heart insufficiency, secondary to pulmonary hypertension, is a negative predictive factor. Genetic and molecular processes underlying left heart ventricle remodeling over the course of pulmonary hypertension remain unknown. In particular, there is no knowledge regarding the mechanisms of left heart ventricle atrophy which was completely avoided by researchers until recently.The aim of this study was to assess changes in protein abundance in left and right heart ventricle free wall of rats in monocrotaline model of PAH.