Participação do Estado Contrátil e do Relaxamento Miocárdico na Disfunção Ventricular durante a Transição Hipertrofia-Falência Cardíaca

Purpose - To investigate the participation of contractile state and relaxation in cardiac muscle dysfunction during the transition from stable hypertrophy to cardiac decompensation in aging spontaneously hypertensive rats (SHR). Methods - isolated left ventricular papillary muscle function was studied in SHR with heart failure (SHR-F), in age-matched SHR without evidence of heart failure (SHR-NF), and in nonhypertensive controls Wistar-Kyoto rats (WKY). Muscles were analised in isometric and isotonic contractions in Krebs-Henseleit solution with calcium concentration of 1.25mM at 28°C. Results - Papillary muscles from SHR-F and SHR-NF demonstrated decreased active tension development and shortening velocity relative to normotensive WKY (p<0.05). SHR-F and SHR-NF did not differ. Compared with SHR-NF and WKY, muscle passive stiffness was increased in the failing SHR (p<0.05 versus WKY and SHR-NF). This parameter did not differ between SHR-NF and WKY (p> 0.05). Conclusion - These data suggest that the progression from stable hypertrophy to heart failure is associated with changes in the passive stiffness and is not related to depression of myocardial contractile function.

Keywords

Heart failure, Hypertrophy, Myocardial function, animal, comparative study, forward heart failure, heart contraction, heart left ventricle function, heart left ventricle hypertrophy, heart right ventricle hypertrophy, hypertension, male, pathophysiology, physiology, rat, Wistar Kyoto rat, Animals, Cardiac Output, Low, Hypertension, Hypertrophy, Left Ventricular, Hypertrophy, Right Ventricular, Male, Myocardial Contraction, Rats, Rats, Inbred WKY, Ventricular Dysfunction, Left