Myocardial Dysfunction of Heart of Rats

Abstract

Food restriction (FR) induces beneficial health effects, such as increased longevity [1], carcino-genesis inhibition [2], reduced acute toxicity of drugs [3], and an improved ability to deal with a wide range of toxic processes from endogenous, physical, biological, and chemical agents [4]. Recent research in our laboratory has shown that FR promotes left ventricular dysfunction [5] and increases contraction and relaxation times in isolated papillary muscle of young normotensive and hypertensive rats [6–9]. The mechanisms behind the changes in myocardial function with FR are still unknown. Several factors may contribute to cardiac dysfunction; they include alteration in excitation–contraction coupling, intrinsic changes in contractile proteins, and impaired autonomic modulation during stress, insufficient energy supply, extracellular matrix changes, and myocyte dropout [10]. In our laboratory, we have observed striking myocardial ultrastructural alterations [9] and calcium handling and beta-adrenergic system changes [8] in young Wistar-Kyoto rats submitted to 50% FR.