Studies on the role of phospholipids in the triglyceride cycle: II. Turnover of plasma phospholipids in ethionine‐treated dogs

Abstract

The disappearance of native labeled plasma phospholipids (nPLP32) was abruptly halted in the plasma of normal mongrel dogs shortly after givingdl‐ethionine by intraperitoneal injection. In other dogs, chronic feeding of ethionine over a period of three days prior to these measurements prolonged the turnover time of plasma phospholipids. This impairment in the turnover of plasma PL brought about by ethionine administration occurs regardless of sex differences in lipid metabolism or other physiological differences relating to the nutritional status of the animal. The amount of nPLP32 found in the liver at the end of the turnover experiments was also measured. These data suggest that phospholipid transport from plasma to liver is not impaired by ethionine. The possible significance of an ethionine‐induced choline deficiency which impairs transport of triglycerides and phospholipids from the liver to plasma is considered in regard to the role of phospholipids in the triglyceride cycle.

Studies on the role of phospholipids in the triglyceride cycle: III. Liver and plasma phospholipid exchange in depancreatized dogs

“…The vehicle for this transport is lipoprotein, the water soluble lipid complexes which have been studied extensively and presented in this symposium by Dr. Lopez (14). Results of previously published portions of the present study (15,16) indicated that liver lipid mobilization required de novo synthesis of liver lecithins.…”

“…Changes in the RSA during the course of fasting suggested increased mobilization of liver PL at times when liver TG cycling would be enhanced. In normal dogs (16), ethionine blocks LIPIDS, VOL. 6, NO.…”

“…1 and 3) were used as unoperated control dogs. The ethionine dosages and the method of acute administration to the dogs were the same as previously described (16). The P32-orthophosphate was administered intravenously and samples of the blood were taken from the femoral artery at several time intervals after the administration of the isotope while the dogs were under pentobarbital anesthesia.…”

“…At about the same time that the blood samples were taken, liver biopsy samples were obtained surgically followed by suturing Gelfoam in the wound area to stop bleeding. Analyses for the total liver lipids, and measurement of specific activity of plasma and liver phospholipids were the same as previously described (15,16). Blood glucose was measured by the method of Kemp et al (18).…”