STUDIES ON THE RAPID ACCUMULATION OF TRIGLYCERIDE IN THE LIVER IN CHOLINE DEFICIENCY

Abstract

Studies with isolated liver perfusion preparations showed that, during 5 to 21 days of choline deficiency (acute phase), the livers fail to release any triglyceride into the perfusate, whereas during 1 to 2 days (early phase) and during 26 to 60 days of choline deficiency (prolonged phase), they tend to release triglyceride into the perfusate at a nearly normal rate. The rate of deposition of hepatic triglyceride in intact rats fed a choline-deficient diet showed a progression complementary to this triphasic pattern of triglyceride release, ie an early phase of slow triglyceride deposition and an acute phase of rapid accumulation followed by the establishment of a higher steady-state level. In the perfusion experiments changes in phospholipid levels in the perfusate followed the same pattern as the triglyceride levels. Increased uptake of free fatty acids by the choline-deficient livers was most marked after 2 days. In vitro additions of choline and several choline derivatives to the 5-day choline-deficient liver perfusion system were unable to restore triglyceride release. Similar studies with blood obtained from choline-supplemented rats showed a very significant restoration of triglyceride release into the perfusate.