Factors Affecting In Vitro Lipogenesis by Bovine Mammary Tissue Slices

Abstract

An in vitro system of fatty acid syn- thesis by bovine mammary tissue slices was developed and characterized. Mam- ary tissue slices were prepared wih a hand microtome and 120 to 150-mg slices incubated in Krebs-Ringer bicarbonate buffer (pH 7.4) at 37 C. Acetate incor- poration into fatty acids and acetate and glucose oxidation to carbon dioxide were linear for 3 h. Mammary tissue was stable and lost no lipogenic capacity for 60 min prior to slicing and incubation if main- tained in isotonic sucrose at 5 or 25 C. Fatty acid synthesis from acetate was maximum at an acetate concentration of 10 mM and a glucose concentration of 5 to 10raM. Insulin had no effect on acetate incorporation into fatty acids by cow mammary tissue slices when varied from physiological to pharmacological concentrations. An examination of lipids synthesized by bovine mammary slices in- dicated that over 70% of the synthesized fatty acids were located in triglycerides with the pattern of fatty acids similar to that produced in vivo. The use of the in vitro system of bovine mammary tissue slice incubations offer an excellent tool for investigation of cellular metabolism and biosynthesis of fatty acids.