Mechanisms involving Ang II and MAPK/ERK1/2 signaling pathways underlie cardiac and renal alterations during chronic undernutrition.

BACKGROUND: Several studies have correlated protein restriction associated with other nutritional deficiencies with the development of cardiovascular and renal diseases. The driving hypothesis for this study was that Ang II signaling pathways in the heart and kidney are affected by chronic protein, mineral and vitamin restriction. METHODOLOGY/PRINCIPAL FINDINGS: Wistar rats aged 90 days were fed from weaning with either a control or a deficient diet that mimics those used in impoverished regions worldwide. Such restriction simultaneously increased ouabain-insensitive Na+-ATPase and decreased (Na++K+)ATPase activity in the same proportion in cardiomyocytes and proximal tubule cells. Type 1 angiotensin II receptor (AT1R) was downregulated by that restriction in both organs, whereas AT2R decreased only in the kidney. The PKC/PKA ratio increased in both tissues and returned to normal values in rats receiving Losartan daily from weaning. Inhibition of the MAPK pathway restored Na+-ATPase activity in both organs. The undernourished rats presented expanded plasma volume, increased heart rate, cardiac hypertrophy, and elevated systolic pressure, which also returned to control levels with Losartan. Such restriction led to electrical cardiac remodeling represented by prolonged ventricular repolarization parameters, induced triggered activity, early after-depolarization and delayed after-depolarization, which were also prevented by Losartan. CONCLUSION/SIGNIFICANCE: The mechanisms responsible for these alterations are underpinned by an imbalance in the PKC- and PKA-mediated pathways, with participation of angiotensin receptors and by activation of the MAPK/ERK1/2 pathway. These cellular and molecular alterations culminate in cardiac electric remodeling and in the onset of hypertension in adulthood.

Bone marrow mesenchymal stromal cells rescue cardiac function in streptozotocin-induced diabetic rats.

OBJECTIVES: In the present study, we investigated whether MSC-transplantation can revert cardiac dysfunction in streptozotocin-induced diabetic rats and the immunoregulatory effects of MSC were examined. BACKGROUND: Cardiac complications are one of the main causes of death in diabetes. Several studies have shown anti-diabetic effects of bone marrow mesenchymal stromal cells (MSC). METHODS/RESULTS: The rats were divided in three groups: Non-diabetic, Diabetic and Diabetic-Treated with 5 × 10(6) MSC 4 weeks after establishment of diabetes. Four weeks after MSC-therapy, systemic metabolic parameters, immunological profile and cardiac function were assessed. MSC-transplantation was able to revert the hyperglycemia and body weight loss of the animals. In addition, after MSC-transplantation a decrease in corticosterone and IFN-γ sera levels without restoration of insulin and leptin plasma levels was observed. Also, MSC-therapy improved electrical remodeling, shortening QT and QTc in the ECG and action potential duration of left ventricular myocytes. No arrhythmic events were observed after MSC-transplantation. MSC-therapy rescued the cardiac beta-adrenergic sensitivity by increasing beta-1 adrenergic receptor expression. Both alpha and beta cardiac AMPK and p-AMPK returned to baseline values after MSC-therapy. However, total ERK1 and p-ERK1/2 were not different among groups. CONCLUSION: The results indicate that MSC-therapy was able to rescue cardiac impairment induced by diabetes, normalize cardiac AMPK subunit expression and activity, decrease corticosterone and glycemia and exert systemic immunoregulation.