Abstract
Summary
The rise in titer of transcholesterin in the sera of rats on different high-fat or atherogenic diets was demonstrated. The reactive component is a serum alpha globulin which appears to combine specifically with cholesterol in agar gel immunoelectrophoresis. The serum cholesterol levels rise in various degrees in relation to diets but they do not correlate directly with transcholesterin titers. The observations suggest that transcholesterin functions as a homeostatic mechanism to meet the excess demands in disposal of cholesterol. The prompt rise of serum transcholesterin titer in rats on the high-fat diets and the moderate hypercholesterolemia may represent the adequacy of transcholesterin function in these animals. On an atherogenic diet, extreme heights of serum total cholesterol are reached early, again with mobilization of transcholesterin, after which the latter declines suggesting the homeostatic effort is approaching exhaustion or that the transcholesterin has been so fully combined that little remains free for further combining. The fall in total serum cholesterol after the peak of transcholesterin titers would be in keeping with the idea that this serum protein (or proteins) has a transport or clearing function for excessive cholesterol. The failure of cholesterol levels to be reduced to a normal range while transcholesterin titers decline is in accord with the concept of homeostatic failure. There was observed further the probable effect of aging upon total serum cholesterol accumulation in some animals on the control diet; this, too, was accompanied by moderate increase in serum transcholesterin titers.
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