Experimental atherosclerosis was induced in rats by feeding the animal with vit. D₂ and atherogenic diet, which was reported previously. In order to examine the mechanism of action of elastase preparation (Eisai, 450 ELU/kg b.w./day), in terms of anti-atherosclerotic effect, calcitonin, an antagonist of vit. D₂ in the calcium metabolism, was administered to the experimentally induced athero-sclerotic rats (calcitonin in the form of elcatonin, a derivative of calcitonin, 0.4 MRCU/kg b.w./day, i. m. injection, made by Toyo Jozo Co.).
1) In the experimentally induced atheroscle-rosis, serum lipids as well as cholesterol, as the total cholesterol, in the artery and in the heart were increased. Cholesterol levels in the artery and in the heart after the fractionation, mainly present in the elastin fraction, were also increased. For such lipids increasing tendency in the experimental stherosclerosis elastase and calcitonin was tend to decrease their levels.
2) In the experimentally induced atheroscle-rosis, the content of the bridge components of lysine origin (isodesmosine, desmosine, merodesmosine, and lysinonorleucine) of the artery was decreased or at least tend to be decreased. Administration of elastase or calcitonin was tend to improve, or normalize such ill tendency.
It may be said that elastase and calcitonin have similar mechanism in the anti-atherosclerotic effect, and metabolic regulation of calcium may be partly related.