Immunolocalization of collagen types I, III and IV, elastin and fibronectin within the heart of normal and copper-deficient rats.

Collagen types I, III and IV, fibronectin and elastin were detected by immunohistochemistry in the normal and copper-deficient rat heart. All rats maintained on a copper-deficient diet for at least 6 weeks were found to have areas of abnormal distribution of these connective tissue components within the endo- and perimysium although the normal appearance observed in control animals prevailed. It appeared that the proliferation of the fibrillar collagens and fibronectin was associated with fibrosis and scar tissue formation. In contrast, the fragmented and disorganized appearance of the myocyte basement membrane and the endomysial elastin did not seem to be associated with the fibrotic process and may be an early indication of copper deficiency. The vascular system of the copper-deficient hearts appeared normal. These results are discussed with reference to the functional and mechanical abnormalities that occur in copper-deficient animals.