Pyridoxamine Protects Against Mechanical Defects In Cardiac Ageing In Rats: Studies On Load Dependence Of Myocardial Relaxation

Our team demonstrated in the past that pyridoxamine attenuated arterial stiffening by targeting the pathogenic formation of glycated collagen cross-links in aged rats. Herein, we examined whether pyridoxamine therapy can protect against mechanical defects in myocardial relaxation by improving arterial wave properties and cardiac contractile performance in senescent animals. Fifteen-month-old male Fisher344 rats were treated daily with pyridoxamine (1gl(-1) in drinking water) for 5months and compared with age-matched untreated control animals (20months old). Arterial wave properties were characterized by wave transit time ((w)) and wave reflection factor (R-f). We measured the contractile status of the myocardium in an intact heart as the left ventricular (LV) end-systolic elastance (E-es). Myocardial relaxation was described according to the time constant of the LV isovolumic pressure decay ((e)). Pyridoxamine therapy prevented the age-associated prolongation in LV (e) and the diminished E-es in senescent rats. The drug also attenuated the age-related augmentation in afterload imposed on the heart, as evidenced by the increased (w) and decreased R-f. We found that the LV (e) was significantly influenced by both the arterial (w) and R-f ((e)=16.3902+8.3123xR(f)-0.4739x(w); r=0.7048, P<0.005). In the meantime, the LV (e) and the LV E-es showed a significant inverse linear correlation ((e)=13.9807-0.0068xE(es); r=0.6451, P<0.0005). All these findings suggested that long-term treatment with pyridoxamine might ameliorate myocardial relaxation rate, at least partly through its ability to enhance myocardial contractile performance, increase wave transit time and decrease wave reflection factor in aged rats.