Comparative aspects of cardiac ultrastructure, morphometry, and electrocardiography of hearts from rats fed restricted dietary copper and selenium

Abstract

Comparative cardiac ultrastructure, morphometry, and electrocardiography after dietary copper and selenium restriction were examined. Male weanling Long-Evans rats were fed diets that were either adequate in both copper and selenium (Cu⁺/Se⁺) or restricted in either Cu (Cu⁻) or Se (Se−) for 8 wk. At wk 8, electrocardiograms (ECG) anddP/dts were obtained and heart tissue was utilized for electron microscopy. Upon examination, Cu⁻ rats were anemic, exhibited a greater heart: body weight ratio, and developed concentric hypertrophy characterized by an enhanced thickening of the left and right ventricular free walls, and interventricular septum. ECG recordings from lead aVF in the Cu⁻ group showed a greater R wave amplitude in comparison to the Cu⁺/Se⁺ group. Se⁻ rats recorded a greater left ventricular +dP/dt _max than both the Cu⁺/Se⁺ and Cu⁻ groups.

Cardiac myofibril volume densities were decreased in both Cu⁻ and Se⁻ rats in comparison to the Cu⁺/Se⁺ rats. In addition Cu⁻ rats showed a greater mitochondria: myofibril ratio. Sarcomere contractile protein disarray was present in both the Cu⁻ and Se⁻ groups. Se⁻ myocytes also showed evidence of edema and mitochondrial fragmentation. The subcellular alterations suggest that similarities exist in the cardiac remodeling processes associated with copper and selenium restrictions.