Author(s): Penitente, Arlete Rita ; Novaes, Rômulo Dias ; Silva, Marcelo Eustáquio ; Silva, Márcia Ferreira da ; Quintão Júnior, Judson Fonseca ; Guatimosim, Silvia ; Cruz, Jader dos Santos ; Chianca Júnior, Deoclécio Alves ; Natali, Antônio José ; Neves, Clóvis Andrade
Date: 2015
Origin: Oasisbr
Subject(s): Intracellular calcium; Cardiovascular pathology; Isolated cardiomyocytes; Malnutrition - morphology
Background: The mechanisms responsible for the cardiac dysfunction associated with dietary protein restriction (PR) are poorly understood. Thus, this study was designed to evaluate the effects of PR on calcium kinetics, basal and β-adrenergic contractility in murine ventricular cardiomyocytes. Methods: After breastfeeding male Fisher rats were distributed into a control group (CG, n = 20) and a protein-restricted group (PRG, n = 20), receiving isocaloric diets for 35 days containing 15% and 6% protein, respectively. Biometric and hemodynamic variables were measured. After euthanasia left ventricles (LV) were collected for histopathological evaluation, SERCA2a expression, cardiomyocytes contractility and Ca2+ sparks analysis. Results: PRG animals showed reduced general growth, increased heart rate and arterial pressure. These animals presented extracellular matrix expansion and disorganization, cardiomyocytes hypotrophy, reduced amplitudes of shortening and maximum velocity of contraction and relaxation at baseline and after β-adrenergic stimulation. Reduced SERCA2a expression as well as higher frequency and lower amplitude of Ca2+ sparks were observed in PRG cardiomyocytes. Conclusion: The observations reveal that protein restriction induces marked myocardial morphofunctional damage. The pathological changes of cardiomyocyte mechanics suggest the potential involvement of the β-adrenergic system, which is possibly associated with changes in SERCA2a expression and disturbances in Ca2+ intracellular kinetics.
