Role of ATP in the inhibition of lipogenesis in fasted animals

Abstract

This study was undertaken to obtain information both in vivo and in vitro on the role of adenosine triphosphate (ATP) in the inhibition of fatty acid synthesis in fasted mice. Fasted mice were injected intravenously with glucose or fructose or intraperitoneally with insulin to increase the supply of endogenous ATP. They then received acetate 1−¹⁴C, glucose 6−³H or fructose U−¹⁴C intravenously and were killed at various intervals. The controls received the labeled tracers only. The radioactivities of liver and carcass fatty acids were determined. The action of ATP on homogenized livers from fasted mice was also determined. The stimulation of lipogenesis was obtained under all these conditions, but only in animals fasted for 4 hr. Insulin was active only on the extrahepatic tissues. Fructose, as well as glucose, restored hepatic lipogenesis. In vitro, ATP restored lipogenesis by homogenized livers of mice fasted for 4 hr, but it inhibited the fatty acid synthesis by homogenized livers from unfasted mice. The significance of the results is discussed.