Improvement of the energy supply and contractile function in normal and ischemic rat hearts by dietary orotic acid

As cardiac performance is closely related to its energy supply, our study investigated the effect of the orotic acid cardioprotective agent on the pathways of energy supply, in both conditions of normal flow and ischemia. Male Wistar rats were fed during nine days with a balanced diet only or supplemented with 1% orotic acid. Dietary administration of orotic acid increased the cardiac utilization of fatty acids, activity of the lipoprotein lipase, expression of the gene of peroxisome proliferator-activated receptor α and its target enzymes. In addition, orotic acid increased the myocardial uptake and incorporation of glucose, glycogen content and level of GLUT4, concentration of glycolytic metabolites and lactate production in both experimental conditions, baseline and after regional ischemia. Thus, in orotic acid hearts there was a simultaneous stimulus of fatty acid oxidation and glycolytic pathway, reflected in increased energetic content even in pre-ischemia. The analysis of the cardiac contractility index showed a positive inotropic effect of orotic acid due, at least in part, to the increased availability of energy. The result allows us to suggest that the metabolic changes induced by orotic acid result in appreciable alterations on myocardial contractile function.