Aging and Cardiac, Biochemical, Molecular and Functional Changes: an Experimental Study

Background: Aging involves physical and psychological changes that reduce the elderly’s ability to adapt themselves to society, which is the leading risk factor for cardiovascular diseases. Objective: To investigate changes in the cardiovascular system resulting from the aging process in rats. Methods: Murinometric/nutritional, echocardiographic and hemodynamic parameters were determined in 1, 5 and 12-month aged male rats. The expression of proteins that are critical to intracellular calcium dynamics and leptin signaling, as well as cardiac ATPase activity, was investigated in cardiac homogenates of rats. Data were expressed as mean ± standard error and analyzed by ANOVA one-way test (* p <0.05 vs. one month and #p <0.05 vs. 5 months). Results: Whereas the body mass index increased (0.46±0.01 g/cm2; 0.75±0.01 g/cm2*,0.78±0.01 g/cm2*), the food efficiency ratio (0.431±0.013; 0.035±0.003*; 0.003±0.001*#), maximum speed during maximal exercise stress testing (3.36±0.34 km/h; 1.38±0.04 km/h*; 1.20±0.13 km/h*) and heart rate (410.2±5.9 bpm; 375.9±7.6 bpm*; 376.6±3,3 bpm*) decreased with age. Left ventricular hypertrophy and diastolic dysfunction along with reduced leptin receptor expression (2.1±0.4; 1.9±0.2; 0.8±0.2*#) and SERCA-type calcium pump activity (1981±77 nmol Pi/mg protein/h; 2 385±205 nmol Pi/mg protein/h; 1 148±152 nmol Pi/mg protein/h#) were observed in the hearts. Conclusions: Aging process is related to cardiometabolic risk, with cardiac leptin receptor downregulation and reduced cardiac SERCA2 calcium pump activity presumably being mechanisms underlying the left ventricular diastolic dysfunction and consequent exercise intolerance.