Aortic medial calcification in progeria-like syndrome.

Aortic medial calcification was investigated in rats in which the progeria-like syndrome (PLS) was evoked by administering dihydrotachysterol. In 35 experimental rats and 15 controls, calcification was studied morphologically by light and electron microscopy, and by enzyme histochemistry. Body weight, food intake and serum calcium levels were also determined. Calcification occurred along and on the elastic lamellae in association with the accumulation of ground substance. In the smooth-muscle cells surrounding the calcified foci, the activities of various lysosomal enzymes increased concomitantly with a tendency toward transformation of smooth-muscle cells to a modified form. From these observations, the role of ground-substance formation by smooth-muscle cells is postulated, and participation in the catabolism of ground substance by the lysosomal enzymes of these cells is suggested. It appears the increased activity of adenosine monophosphatase should be linked to the calcification. The etiology of weight loss, skin manifestations and aortic calcification in PLS rats seems to be different from that in human progeric diseases. Therefore, the PLS rat should not be readily accepted as an animal model for the study of progeric diseases.