Spontaneous and dietary‐induced cardiovascular lesions in DBA mice

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Abstract
In DBA mice, 12–16 months of age, receiving an adequate commercial diet the incidence of ventricular myocardial necrosis and calcification was 48% and that of pericardial calcification was 12%. Atrial thrombosis did not occur. Young adult mice of the same strain were fed a high‐fat (28% lard), low‐protein (8% casein) diet, with and without lipotropic supplement of betaine, for 48 weeks. The incidence of ventricular myocardial necrosis and calcification increased significantly over the spontaneous level with the greatest frequency (95%) occurring in the betaine‐supplemented group. Pericardial calcification also increased with the highest incidence (100%) in the non‐supplemented animals. Dietary induced atrial thrombosis reached lethal dimensions (80%) for most animals in the betaine‐supplemented group within 12 weeks. The non‐supplemented animals had less atrial thrombosis (50%) and greater longevity. Frequency and types of lesions observed were similar to those which occur in other strains of mice fed the same diet. The genetic susceptibility to spontaneous cardiac lesions did not appear to predispose the DBA mice to a greater sensitivity to dietary induced lesions, but may have contributed to the calcification which characterized the lesions. Dietary betaine seemed to influence significantly the production of a higher incidence of cardiac damage.