Cardiac dysfunction induced by low and high diet antioxidant levels comparing selenium and vitamin E in rats

The present study was designed to investigate and compare the effects of di etary antioxidants on the mechanical characteristics of the rat heart. Both sex weanling rats were fed for 12 to 14 weeks a standardized selenium (Se) - and vitamin E-deficient diet, a Se-excess diet, or a control diet. Defici ency or toxicity of Se was verified by direct (tissue Se analysis and histo pathological investigations) methods. The hearts of both experimental group s revealed some alterations in contractile performance with increased heart rate and coronary perfusion pressure. The average peak contractile force o f the electrically stimulated papillary muscle measured in both experimenta l groups was not significantly different from the control values. When expr essed as a percentage, the maximal increase in the peak contractile force o f papillary muscle (PCF) that was obtained with 100 nM isoproterenol, respe ctively, was less in both experimental groups (26% in PCF of deficient grou p; 34% in PCF of rich group) than in the control group (80% in PCF). A decr eased stimulation of contractile force of papillary muscle strips by a beta -adrenergic agonist seems to be in agreement with possible alterations in t he response to inotropic agents due to a modification of the receptor funct ion. (C) 1999 Academic Press.