Basal and �-Adrenergic Cardiomyocytes Contractility Dysfunction Induced by Dietary Protein Restriction is Associated with Downregulation of SERCA2a Expression and Disturbance of Endoplasmic Reticulum Ca²⁺Regulation in Rats

Abstract

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.

Protein Restriction in the Peri-Pubertal Period Induces Autonomic Dysfunction and Cardiac and Vascular Structural Changes in Adult Rats

“…This work demonstrates that dietary protein restriction in peri-pubertal period followed by 60 days of nutritional recovery results in hypertension in young adulthood which appears to be underpinned by sympathetic hyperactivity. This is the first demonstration of adult neurogenic hypertension programmed in the peri-pubertal period, while other studies have addressed the effect of low protein diet on blood pressure just after the exposure to the insult ( Loss et al, 2007 ; Penitente et al, 2007 ; Del Carmen Miñana-Solis and Escobar, 2008 ; Martins et al, 2011 ; Murca et al, 2012 ; Gomide et al, 2013 ; Penitente et al, 2014 ; Cappelli et al, 2018 ). In the context of DOHaD concept the studies have explored an earlier susceptible window of development, the peri-natal period ( Latorraca et al, 1998 ; De Oliveira et al, 2011 ; De Brito Alves et al, 2014 ; De Oliveira et al, 2014 ; Nascimento et al, 2014 ; Barros et al, 2015 ; De Oliveira et al, 2016 ; Ferreira et al, 2016 ; Paulino-Silva and Costa-Silva, 2016 ; Rossini et al, 2017 ; Barros et al, 2018 ; Martins et al, 2018 ; Assalin et al, 2019 ; Ferreira et al, 2019 ).…”

“…These changes may be dependent on precocious changes to cardiac structure induced by the early insult. Previous studies point to an increase in blood pressure and sympathetic activity immediately after the caloric-protein insult during post-weaning/peri-pubertal period ( Loss et al, 2007 ; Penitente et al, 2007 ; Murca et al, 2012 ; Penitente et al, 2014 ). We suggest that the autonomic dysfunction and hypertension observed in the present adult LP animals, exposed to protein restriction in peri-puberty, may be an indicative of hypertension developed in the peri-pubertal period that was maintained until adulthood.…”

“…We have previously demonstrated metabolic disfunction in adult animals exposed to dietary protein restriction during puberty/adolescence ( De Oliveira et al, 2013 ; De Oliveira et al, 2018 ). Furthermore, experimental studies in models of malnutrition in post-weaning/peri-puberty indicate that hypertension ( Loss et al, 2007 ; Penitente et al, 2007 ; Murca et al, 2012 ; Penitente et al, 2014 ) and vascular sympathetic hyperactivity ( Martins et al, 2011 ) occur immediately after the exposure period, and these may be associated with a central glutamate disorganization ( Rodrigues et al, 2012 ). However, the long-term cardiovascular dysfunction in this model has not yet been evaluated, pointing to a hole in the literature concerning the programming of hypertension induced by insults during adolescence or the peri-pubertal period.…”

Dense optical flow software to quantify cellular contractility

“…An important parameter for the analysis of the isolated CM is contractility, which provides information that reflects its cellular function. Measurements of contractility have been widely used for research on both adult and neonatal myocytes ( Belostotskaya and Golovanova, 2014 ; Berger et al., 1994 ; Boudreau-Béland et al., 2015 ; Harary and Farley, 1960 ; Haworth et al., 1987 ; Hissa et al., 2017 ; Jesus et al., 2020 ; Penitente et al., 2014 ; Ramadan et al., 2018 ). More recently, human induced pluripotent stem cell-derived CMs (hiPSC-CMs) have been employed as a model for human cardiac disease and drug screening ( Ballan et al., 2020 ; Birket et al., 2015 ; Gong and Sobie, 2018 ; Lahti et al., 2012 ; Lan et al., 2013 ; Ribeiro et al., 2015 ; Wang et al., 2014 , 2019 ).…”

Ventricular Fibrosis and Coronary Remodeling Following Short-Term Exposure of Healthy and Malnourished Mice to Bisphenol A

“…Postweaning LP diet was previously associated with LV hypertrophy and increased cardiac contractility and +dP/dt and -dP/dt values in adult life (Murca et al, 2012;de Belchior et al, 2016). In contrast, impaired cardiomyocyte contractility, lower calcium amplitude, reduced cardiomyocyte size, and increased number of collagen fibers in the LV myocardium in response to a postweaning LP diet was reported (Penitente et al, 2013(Penitente et al, , 2014. Such differences may be related to the stage of the hypertensive disease induced by postweaning protein restriction (Mendes et al, 2017) as well as to differences in LP diet composition.…”