The effects of cholesterol dosage, cortisone, and DCA on total serum cholesterol, lipoproteins, and atherosclerosis in the rabbit

The effects of cholesterol dosage, cortisone, and desoxycorticosterone acetate on total serum cholesterol, lipoproteins, and atherosclerosis were studied over a period of 112 days in thirty-two rabbits. Cholesterol was administered by feeding the rabbits diets containing 0.063, 0.25, and 1.0 per cent cholesterol At intervals measurements were made of total serum cholesterol and of low density lipid and lipoprotein components of three classes, S_f, 5–9, S_f 10–15, and S_f 16–30. All three classes of lipoproteins increased with cholesterol feeding. The total serum cholesterol concentration was linearly related to both the quantity of cholesterol consumed and its concentration in the diet. Lipoprotein and total serum cholesterol concentrations were significantly and equally well correlated with the severity of atherosclerosis. Cortisone administration in the normal rabbit increased the concentrations of total cholesterol and of lipoprotein components of the S_f 10–15 and S_f 16–30 classes, but did not produce atherosclerosis. Cortisone treatment in cholesterol-fed rabbits did not significantly affect the levels of serum lipoproteins, cholesterol concentration, or atherosclerosis produced by a 1.0 per cent cholesterol diet alone. Values for total cholesterol and S_f 5–9 class of lipoproteins in DCA-treated animals were lower than those in controls but the degree of atherosclerosis was not significantly less.

Effect of electrolytes on arterial muscle contraction

The effect of specific electrolyte changes and of desoxycorticosterone on the responsiveness of vascular smooth muscle to epinephrine was studied using rabbit aortic strips. Low sodium increases, while high sodium decreases the epinephrine response. Conversely, low potassium decreases, while high potassium increases the epinephrine response. Desoxycorticosterone potentiates the epinephrine response in a manner qualitatively similar to that of high potassium, but different from that of low sodium potentiation.

Conditioning by cortisol for the production of acute massive myocardial necroses during neuromuscular exertion

Following pretreatment with cortisol and NaH 2 PO 4 , a brief period of neuromuscular stress regularly produces massive myocardial necroses in the rat. Pretreatment with desoxycorticosterone and the phosphate is less effective in this respect.