Cadmium, an environmental pollutant, has implicated in the pathogenesis of cardiovascular diseases. Biochemical and pathophysiological changes characterized by arterial hypertension, accelerated cholesterol plaque formation on arterial walls, cardiac conduction abnormalities, and reduction in myocardial contractility have been reported in experimental animals chronically exposed to low concentration of cadmium. This study was undertaken to evaluate the ultrastructural changes of the cardiac muscle in rats exposed to cadmium chloride and to ascertain whether these changes are modified after discontinuation of cadmium feeding.

Wistar strain rats(body weight 200~250gram) were injected intraperitoneally once weekly with 3.75mg/kg of cadmium chloride for 10 weeks and were sacrificed at 1 day, 1 week and 2 weeks after discontinuation of cadmium administration.

Ultrastructure if rat cardiac muscle fibers after cadmium administration revealed that mitochondria were increased in number and their cristae were severely damaged. Cardiac myofibrils and myofilaments were reduced. Z-disc were partly dislocated and A-bands and I-bands were not clearly defined. Irregularly arranged intercalated disc and disrupted sarcolemma were also found. These structural alterations resulting from cadmium feeding were partly reduced after removal of cadmium exposure for 2 weeks. These structural alterations resulting from cadmium feeding were partly reduced after removal of cadmium exposure for 2 weeks.

It is suggested that exposure to cadmium chloride was associated with cardiac ultrastructural changes which might be responsible for physiologic abnormalities and these alterations may be partly reversible after discontinuation of cadmium administration.