[Mitochondrial Antioxidant Plastomitin Improves Cardiac Function in Doxorubicin-Induced Cardiomyopathy]

Compensatory Changes of the Diastole under Conditions of Inflow Restriction to the Heart

This work was designed to study changes in the mechanical properties of rat myocardium during short-term (2-3 sec) compression of the lower vena cava. A catheter was inserted into the left ventricle, allowing simultaneous measurement of left-ventricular volume and pressure. The decrease in the left-ventricular end-diastolic volume caused by inflow restriction was accompanied by less pronounced decrease in the left-ventricular stroke volume and maximum rate of left-ventricular pressure development. This was coincided with accelerated relaxation and deeper fall of the minimum left-ventricular diastolic pressure. The lower was left-ventricular end-systolic volume, the greater was the degree of these changes. It is assumed that the "restoring force" that naturally appears under conditions of low filling of the left ventricle is determined by elastic N2B part of the titin molecule that is compressed during strong shortening of myofibrils and accelerates their return to the previous length during relaxation. As a result of better filling of the left ventricle, the heart can maintain left-ventricular stroke volume at the appropriate level.

[Prevention of Diastolic Dysfunction Caused by Doxorubicin by Mitochondrial Antioxidant Plastomitin]

Aim      An attempt to prevent the development of diastolic dysfunction (DD) with the mitochondrial antioxidant plastomitin on a model of doxorubicin-induced cardiomyopathy. DD is a type of chronic heart failure. Due to the increasing number of patients with this condition and the absence of effective therapy, development of means for DD correction is a relevant objective.Material and methods  Cardiomyopathy was modeled in 17 rats by two subcutaneous injections of doxorubicin 2 mg/kg/week. The other group (n=17), also administered with doxorubicin, received plastomicin 0.32 mg/kg daily subcutaneously. Left ventricular function was evaluated with echocardiography (EchoCG) and cardiac catheterization with simultaneous pressure and volume monitoring.Results According to EchoCG data the ejection fraction remained unchanged in the experimental groups. Cardiac catheterization showed disorders of both myocardial contractility and relaxability only in the doxorubicin group.Conclusion      A course of plastomitin in combination with the doxorubicin treatment can maintain normal heart contractility and thereby, prevent the known doxorubicin cardiotoxicity.