Movement of lipids into and out of the blood during hyperlipidemia induced in rabbits by pituitary extract and fraction H.

Rabbits were rendered hyperlipidemic by the subcutaneous injection of an alkaline aqueous extract of mammalian pituitary gland or a partially purified, concentrated fraction derived therefrom, designated Fraction H. Eight hours after the injection of Fraction H, arteriovenous (A-V) differences in plasma triglyceride (TG) were measured across five body areas. A large negative A-V difference in plasma TG was consistently found across the liver (increase in plasma concentration), and a moderate positive A-V difference across the perirenal fat depot (decrease in plasma concentration).

Changes in blood coagulation during the clearing of lipid emulsions by lipoprotein lipase.

The clearing of lipid emulsions by postheparin plasma from rabbits or human beings was accompanied regularly by a sharp reduction in the recalcification time of the plasma. No change in blood coagulation took place when the activity of lipoprotein lipase, the clearing enzyme, was inhibited by means of heat or the action of a surface-active agent. In control studies, the recalcification time of postheparin plasma was not altered by the addition of glycerol, free fatty acids, or the products of hydrolysis of a lipid emulsion.

Inhibition of lipoprotein lipase activity following injection of pituitary extracts into rabbits.

Rabbits given a single subcutaneous injection of an alkaline extract of hog, bovine, or human anterior pituitary glands developed marked hyperlipemia within 12 to 24 hours. The injections in some instances were followed by sickening and death of the animal, though no anatomical changes responsible for these consequences could be determined. No such sequelae were observed in animals given much larger injections of comparable extracts made from other tissues.

The pathogenesis of hyperlipemia induced by means of surface-active agents. II. Failure of exchange of cholesterol between the plasma and the liver in rabbits given triton WR 1339.

Rabbits subjected to subtotal hepatectomy failed to develop increased serum cholesterol levels following parenteral injection of triton WR 1339, the finding indicating that the liver is essential for the establishment of the hypercholesterolemia induced by surface-active agents. The cholesterol content of the livers of rabbits rendered hyperlipemic by means of triton remained unchanged both during the rapid rise of the serum cholesterol levels and during the return to normal values. By contrast, the cholesterol content of the livers of rabbits fed cholesterol rose progressively over a period of 5 weeks, concommittant with the increase in serum cholesterol levels.

The pathogenesis of hyperlipemia induced by means of surface-active agents. I. Increased total body cholesterol in mice given triton WR 1339 parenterally.

Mice rendered hyperlipemic by means of intravenous or subcutaneous injections of triton WR 1339 were found to have an increase in the total amount of cholesterol in their bodies. This observation indicates that the injected surface-active agent affects the metabolism of cholesterol and brings about hyperlipemia by augmenting the synthesis of lipides, or by interfering with their degradation or excretion, or by some combination of these factors. The implications of the findings for the pathogenesis of the hyperlipemia induced by triton are discussed further in the accompanying paper (16).