Effect of high dietary selenium on the ultrastructure of cardiac muscle cells in the rabbit

The purpose of this study was to investigate the effect of long-term high d ietary selenium intake on myocardial ultrastructure in rabbits. One-month-o ld male and female rabbits were fed with either selenium (Se) excess (4.2 m g Se/kg diet) or a selenium adequate (0.23 mg Se/kg diet) diet for 3 months . Myocardial tissue was processed for transmission electron microscopy and light microscopy. Degenerative changes indicating disintegration of interna l structure were observed in the myocytes of the heart muscle of Se-supplem ented animals, while the myocardium of animals fed a Se-adequate diet was n ormal ultrastructurally. Degenerative changes were mainly disruption of myo fibrils, marked cavitation of space and irregular sarcomeres. There were di stortions in the region of intercalated discs, mitochondrial alterations wi th a different distribution through the myocardial fibres and poorly develo ped and disorganized cristae. The excess Se in the diet caused marked myoca rdial alterations, particularly in the mitochondrial matrix of myocytes. Ch anges in the mitochondria were considered to be evidence of irreversible ce ll injury induced by long-term high dietary Se intake. Med Sci Res 27:795-7 99 (C) 1999 Lippincott Williams & Wilkins.