Myofibrillar and Nonmyofibrillar Myocardial Proteins of Copper-Deficient Rats

Abstract

Myofibrillar and nonmyofibrillar proteins from hearts of copper-adequate (n = 9) and copper-deficient (n = 10) rats were compared. Male weanling Long-Evans rats were fed copper-deficient or copper-adequate diets for 9 wk. Twelve additional rats were fed similar diets and cardiac tissue was evaluated by transmission electron microscopy. Ventricular myocytes were glycerinated and homogenized in 0.1 M KCl and 1.5% Triton X-100, and suspensions were centrifuged at 1100 x g. The supernatant was removed and designated Triton X-100-soluble non-myofibrillar protein, and the pellet was resuspended and recentrifuged several times to obtain myofibrillar protein. Sodium dodecyl sulfate--polyacrylamide gel electrophoresis (SDS-PAGE) analysis was conducted on both protein fractions. Densitometer scans of SDS-PAGE pherograms of myofibrillar protein revealed no significant difference between copper-adequate and copper-deficient groups. Similar analysis of nonmyofibrillar protein revealed a consistent decrease or diminished level of a 23-kDa polypeptide among copper-deficient rat hearts. These results may be consistent with the findings that demonstrated fragementation of mitochondrial cristae and an increased area occupied by mitochondria in copper-deficient rat hearts.