Stimulatory effect of glucose upon triglyceride synthesis from acetate, decanoate, and palmitate by mammary gland slices from lactating mice.

Slices prepared from the mammary glands of lactating mice incorporate only small amounts of (1--14C) acetate, (1--14C) decanoate, or (1--14C) palmitate into lipids. However, when glucose is added to the incubation medium, fatty acid incorporation is stimulated-13-fold from acetate, 17-fold from decanoate, and 2-fold from palmitate. Over 90% of the -14C activity in the lipid fraction is in triglycerides. Analysis of fatty acids in the triglycerides showed that almost all of the decanoate and the palmate were incorporated as intact molecules, while acetate yielded acids of varying chain lengths. The glucose stimulation of triglyceride synthesis is not solely due to its effect upon chain elongation but also could involve glyceride-glycerol availability, as well as other unknown factors. However, from measurements of the amounts of glycerol 3-phosphate in the tissue incubated in the presence of palmitate, it would appear that glyceride-glycerol availability is not rate limiting in triglyceride synthesis.